Semiconductor Package Warpage Control via Differential Thermal Expansion
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Solution Overview
Problem
Semiconductor packages face warpage issues due to differences in thermal expansion coefficients between the package substrate and the semiconductor chip, leading to upward bending, which existing technologies fail to adequately address.
Innovation Solution
A semiconductor package design featuring an upper structure with a die attach film, reinforcing plate, and insulating layer, and a lower structure with a conductive pattern and insulating layers, where the thermal expansion coefficients of the upper and lower structures differ by at least 30 ppm, to manage thermal expansion and suppress warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the package substrate and semiconductor chip have similar thermal expansion coefficients, then thermal stress is reduced, but the ability to suppress upward bending and maintain package flatness is insufficient
Solution Approach 1:
The patent employs composite material structures with different thermal expansion coefficients. The upper structure (including upper insulating layer and upper solder resist) has a higher thermal expansion coefficient than the lower structure (lower insulating layer), creating a differential expansion mechanism that generates counteracting stresses to suppress upward bending of the package substrate.
Solution Approach 2:
The patent applies different material properties to different regions of the package structure. Specifically, the upper structure uses materials with higher thermal expansion coefficients compared to the lower structure, creating localized thermal expansion characteristics that balance the overall package flatness during temperature variations.
2Manufacturing precision
If a simple package structure is used, then manufacturing is easier, but warpage control due to thermal expansion differences is inadequate
Solution Approach 1:
The patent controls warpage by carefully selecting and adjusting the thermal expansion coefficient parameter of materials in different structural layers. The upper structure is designed with materials having higher thermal expansion coefficients than the lower structure, creating a parameter differential that actively compensates for thermal warpage during manufacturing and operation.
3Reliability
If the upper structure has higher thermal expansion coefficient, then upward bending is suppressed, but material selection and manufacturing precision requirements increase
Solution Approach 1:
The patent directly utilizes the thermal expansion phenomenon to solve the warpage problem. By designing the upper structure with materials having higher thermal expansion coefficients than the lower structure, the patent creates a differential expansion mechanism that generates internal stresses counteracting the upward bending tendency of the package substrate during temperature cycles.
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 effectively suppresses warpage by ensuring the upper structure expands more than the lower structure, maintaining package flatness and preventing upward bending, thereby enhancing the reliability and stability of the semiconductor package.
Implementation Method 1
an upper structure over the semiconductor chip, the upper structure having a first thermal expansion coefficient; and a lower structure under the semiconductor chip, the lower structure having a second thermal expansion coefficient of less than or equal to the first thermal expansion coefficient
Data Source
AI summary
Provided is semiconductor package, including a semiconductor chip; an upper structure over the semiconductor chip, the upper structure having a first thermal expansion coefficient; and a lower structure under the semiconductor chip, the lower structure having a second thermal expansion coefficient of less than or equal to the first thermal expansion coefficient.