Package Substrate Cutting Regions for Warpage Reduction
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Solution Overview
Problem
The increasing integration density of electronic products leads to warpage issues in package substrates due to differences in thermal expansion coefficients between semiconductor chips, epoxy molding compounds, and package substrates, causing shrinkage and warpage during the fabrication process.
Innovation Solution
The fabrication method involves creating cutting regions in the package substrate core portion, which are filled with an insulating material, to prevent stress transfer between circuit portions and reduce warpage. These cutting regions can be slit-type or trench-type, extending in specific directions to disconnect stress application and maintain substrate stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the integration density of electronic products is increased, then the area ratio of semiconductor chip to package substrate is improved, but warpage and shrinkage of the package substrate worsen due to differences in thermal expansion coefficients
Solution Approach 1:
The package substrate is divided into multiple independent regions by forming cutting regions that extend through the substrate thickness. These cutting regions create separate stress zones that prevent warpage from propagating across the entire substrate, allowing high integration density while maintaining local stability in each segmented region.
Solution Approach 2:
An insulating layer is introduced as an intermediary material filling the cutting regions. This insulating layer acts as a stress buffer between different substrate regions, accommodating thermal expansion differences while maintaining electrical insulation. The insulating layer prevents direct stress transfer between circuit portions, reducing overall substrate warpage.
2Length of moving object
If the thickness of package substrate is decreased to make products thinner, then the compactness of package product is improved, but warpage caused by thermal expansion differences worsens
Solution Approach 1:
By segmenting the thin substrate into isolated regions through cutting regions, the patent prevents warpage from affecting the entire substrate. Each segmented region can independently accommodate thermal stress without causing global warpage, enabling the use of thinner substrates while maintaining stability.
Solution Approach 2:
The cutting regions create local structural variations within the thin substrate. The insulating material filling these regions provides localized stress relief zones with different mechanical properties, allowing the thin substrate to maintain overall stability despite thickness reduction.
3Stability of the object's composition
If cutting regions are formed to prevent stress transfer and reduce warpage, then substrate stability is improved, but fabrication process complexity worsens
Solution Approach 1:
The formation of cutting regions and the filling with insulating material are combined into a single integrated process step. The insulating layer is applied to cover both the substrate surface and fill the cutting regions simultaneously, reducing the number of separate fabrication steps while achieving both stress relief and electrical insulation.
Solution Approach 2:
The insulating layer serves multiple functions simultaneously: it provides electrical insulation between circuit portions, fills the cutting regions to prevent stress transfer, and maintains substrate structural integrity. This multi-functionality reduces the need for additional specialized components or process steps.
4Reliability
If cutting regions are filled with insulating material to maintain electrical insulation, then electrical performance is improved, but manufacturing steps increase
Solution Approach 1:
The insulating layer formation process is designed to simultaneously perform multiple functions: covering the substrate surface for electrical insulation and filling the cutting regions for mechanical stress relief. This merging of functions into a single process step prevents the need for separate insulation and stress relief treatments.
Solution Approach 2:
The insulating material serves dual purposes: providing electrical insulation between circuit portions and acting as a stress buffer in the cutting regions. This multi-functionality eliminates the need for additional manufacturing steps dedicated solely to stress management, simplifying the overall fabrication process.
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 solution effectively reduces substrate shrinkage and warpage, preventing damage during assembly and delivery, while simplifying the fabrication process by using thermal compression to fill the cutting regions with insulating material.
Implementation Method 1
thermal compression to fill the cutting regions with insulating material
Data Source
AI summary
A package substrate includes a core portion comprising a first surface and a second surface arranged opposite to each other; first cutting regions provided to penetrate at least a portion of the core portion in a thickness direction; a first upper circuit pattern disposed on the first surface of the core portion; and an insulating layer provided to cover the first surface of the core portion and to fill the first cutting regions. The first cutting regions are spaced apart from each other in a first direction that is substantially parallel to one side of the core portion.