TCB Package Bonding Structure for Coplanarity and Low Warpage
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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 to maintain consistent heights during solder bump reflow, forming column or hourglass-shaped joints to improve coplanarity and prevent warpage, using vacuum forces to hold workpieces during heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If convection-type reflow is used to bond semiconductor chips to package substrates, then throughput is improved, but thermal budget increases causing warpage and delamination
Solution Approach 1:
The patent replaces convection-type thermal reflow with thermal compression bonding (TCB), which uses direct thermal contact through a TCB bonding head and vacuum chuck table instead of convection heating. This substitution reduces thermal budget while maintaining bonding effectiveness, thereby reducing warpage and delamination risks while preserving throughput.
Solution Approach 2:
The patent introduces a TCB bonding head and vacuum chuck table as intermediary components that facilitate direct thermal contact between the heating source and the workpiece. This intermediary system enables controlled thermal compression bonding, allowing efficient heat transfer with reduced thermal budget compared to convection-type reflow.
2Object-affected harmful factors
If thermal compressive reflow is used to reduce thermal budget, then warpage and delamination are reduced, but consistent height control during heating is challenging
Solution Approach 1:
The patent employs vacuum forces through the TCB bonding head and chuck table to hold workpieces in a fixed position during heating. This vacuum holding mechanism provides feedback control that maintains consistent height and prevents workpiece movement, ensuring uniform joint shapes (column or hourglass) throughout the thermal compression bonding process.
Solution Approach 2:
The patent uses vacuum suction to create equipotential positioning of workpieces on the TCB bonding head and chuck table. By applying uniform vacuum forces across the workpiece surfaces, the system maintains consistent height and orientation during heating, eliminating height variations that would otherwise occur during thermal compression bonding.
3Manufacturing precision
If vacuum forces are applied to hold workpieces during TCB, then height consistency is improved, but device complexity increases
Solution Approach 1:
The TCB bonding head and vacuum chuck table are designed to perform multiple functions: they provide thermal contact for heating, apply vacuum forces for positioning, and maintain compression during bonding. This multi-functionality reduces the need for separate positioning and heating systems, thereby limiting the increase in device complexity while achieving height consistency.
Solution Approach 2:
The patent merges the heating function and positioning function into a single integrated TCB bonding head and chuck table system. By combining thermal compression and vacuum holding in one system, the patent achieves height consistency without requiring separate complex positioning mechanisms, thus limiting the overall device complexity increase.
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 in semiconductor device packages, ensuring better connections between substrates and printed circuit boards by maintaining uniform joint shapes and preventing deformation.
Implementation Method 1
a first substrate is attached to a vacuum chuck table through vacuum suction
Implementation Method 2
a position of the TCB bonding head relative to the vacuum chuck table is adjusted such that a height between a topmost surface of the first conductive pillar and a bottommost surface of the first solder bump is maintained during heating
Implementation Method 3
heating the TCB bonding head to adhere the first solder bump to the first conductive pillar
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.