Packaging Substrate Dummy Layer for CTE Mismatch Control
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Solution Overview
Problem
Current semiconductor packaging technologies face challenges in efficiently managing thermal expansion differences between glass or silicon substrates and insulating materials, leading to issues like delamination and cracking during heat treatment processes.
Innovation Solution
Incorporating a dummy layer with a lower Coefficient of Thermal Expansion (CTE) than the insulating materials, positioned between the core layer and the distribution layers, to mitigate stress and prevent delamination or cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass or silicon substrate is used as the core layer, then high-performance and high-frequency semiconductor devices can be mounted, but thermal expansion differences cause delamination and cracking during heat treatment
Solution Approach 1:
A dummy layer with intermediate CTE value is introduced between the core layer and distribution layers. This dummy layer acts as a stress buffer that mediates the thermal expansion differences between the glass/silicon substrate (low CTE) and the insulating materials (high CTE), preventing direct stress transmission that causes delamination and cracking.
Solution Approach 2:
The CTE parameter of the dummy layer is specifically selected to be between the CTE values of the core layer and distribution layers. By changing the material composition of the dummy layer (containing inorganic particles with appropriate CTE), the thermal expansion characteristics are optimized to reduce stress during temperature changes.
2Ease of manufacture
If insulating materials with high CTE are used in distribution layers, then ease of manufacture is improved, but thermal stress causes delamination from the core layer
Solution Approach 1:
The dummy layer serves as an intermediary between the insulating distribution layers and the glass/silicon core layer. It allows the use of easily manufacturable insulating materials with higher CTE while preventing bonding failure by absorbing the thermal expansion mismatch stress.
Solution Approach 2:
The dummy layer is constructed as a composite material containing inorganic particles (such as alumina or silica) dispersed in a resin matrix. This composite structure provides both the ease of manufacture associated with resin-based materials and the controlled CTE properties needed to maintain bonding stability.
3Productivity
If the pitch of wiring is reduced to increase device density, then productivity is improved, but manufacturing precision becomes more difficult due to material limitations
Solution Approach 1:
By changing the CTE parameter of the dummy layer to match intermediate values, the thermal stress during manufacturing processes is reduced. This creates a more stable manufacturing environment that enables precise wiring pitch control even at reduced pitches, supporting higher device density.
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 dummy layer effectively distributes thermal stress, preventing delamination and cracking of the core layer, and enhancing the reliability and durability of the packaging substrate during manufacturing and operation.
Implementation Method 1
The dummy layer comprises a material having a lower Coefficient of Thermal Expansion (CTE) than a CTE of an insulating material of the first distribution layer
Data Source
AI summary
A method for manufacturing a packaging substrate and a packaging substrate using the method are provided. A packaging substrate includes a core layer and an upper layer disposed on the core layer. The core layer includes a glass core having a first face and a second face facing each other. The upper layer includes a first distribution layer formed on the core layer, and a dummy layer formed on the first distribution layer. The dummy layer may include a material having a lower coefficient of thermal expansion (CTE) than a CTE of an insulating material of the first distribution layer.