Semiconductor Package Substrate Layout for Lower-Temperature Flip Chip Bonding
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Solution Overview
Problem
In flip chip bonding methods using convection reflow equipment, thermal stresses on semiconductor chips are significantly increased due to the application of heat to the entire substrate, and high target temperatures are required for bonding quality in laser-assisted bonding (LAB) processes, leading to potential substrate warpage and yield reduction.
Innovation Solution
A semiconductor package design incorporating a mounting substrate with insulation layers, substrate pads, heat absorbing pads, and connection lines that thermally couple these pads, allowing heat from peripheral heat absorbing pads to be transferred to second substrate pads, reducing the need for high laser temperatures during bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If convection reflow equipment is used to apply heat to the entire substrate for bonding, then bonding quality is improved, but thermal stresses on the semiconductor chip are significantly increased
Solution Approach 1:
The patent extracts the heat application function from the entire substrate and localizes it to specific regions. By using laser-assisted bonding with heat absorbing pads positioned at specific locations, only the necessary areas are heated, eliminating the thermal stress caused by heating the entire substrate while maintaining bonding quality.
Solution Approach 2:
The patent implements local quality by creating heat absorbing pads with specific thermal properties at predetermined locations on the substrate. These pads have different thermal characteristics compared to the surrounding substrate, allowing localized heat absorption and distribution to reduce thermal stress while ensuring proper bonding.
2Stress or pressure
If laser assisted bonding is used to reduce thermal stresses, then thermal stress is reduced, but a high target temperature must be set for bonding quality
Solution Approach 1:
The patent introduces heat absorbing pads as intermediary elements between the laser source and the substrate. These pads act as thermal mediators that absorb laser energy and distribute it locally, enabling effective bonding at lower target temperatures while maintaining reduced thermal stress benefits.
Solution Approach 2:
The patent changes the thermal parameters of specific substrate regions by incorporating heat absorbing pads with different thermal conductivity and heat capacity. This allows optimization of the laser bonding process to achieve effective bonding at lower temperatures while maintaining the stress-reduction advantage.
3Reliability
If high target temperature is set for laser bonding, then bonding quality is improved, but substrate warpage and yield reduction occur
Solution Approach 1:
The patent extracts the heat generation function from the entire substrate and concentrates it in specific heat absorbing pad regions. This localized heat application achieves necessary bonding quality while preventing the excessive heating that causes substrate warpage and yield reduction.
Solution Approach 2:
By creating regions with different thermal properties through heat absorbing pads, the patent enables localized heat management. This ensures sufficient heat for bonding quality in critical areas while preventing excessive temperature rise in other regions that would cause warpage and yield loss.
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 design improves bonding strength and reduces thermal stress-related warpage and yield loss by effectively distributing heat, enhancing the bonding process and structural stability.
Implementation Method 1
connection lines configured to thermally couple the heat absorbing pads and the second substrate pads to each other
Implementation Method 2
a laser may be irradiated onto the semiconductor chip disposed on a mounting substrate to reflow a solder
Implementation Method 3
heat absorbing pads on the upper surface in a peripheral region of the mounting surface adjacent to the chip mounting region
Data Source
AI summary
Provided is a mounting substrate for a semiconductor package, including a substrate having an upper surface and a lower surface opposite to each other, the substrate including a plurality of insulation layers and wirings in the plurality of insulation layers, first substrate pads and second substrate pads on the upper surface in a chip mounting region of the mounting surface, heat absorbing pads on the upper surface in a peripheral region of the mounting surface adjacent to the chip mounting region, and connection lines in the substrate, the connection lines being configured to thermally couple the heat absorbing pads and the second substrate pads to each other.