Organic Substrate Thermal Warp Control via Layered Material Removal
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Solution Overview
Problem
Organic substrates used in electronic packages face challenges in maintaining optimal warp characteristics at room temperature and reflow conditions, leading to reduced yields due to asymmetric thermomechanical properties and potential convex shape formation during reflow, which hampers chip joining efficiency.
Innovation Solution
The solution involves creating an organic substrate with strategically designed top and bottom layers, including optional core layers, where material is removed from specific patterns on these layers to control thermal warp, ensuring a Shape Inversion Temperature above reflow temperature, thus maintaining a concave shape conducive to chip joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If material is removed from specific patterns on top and bottom layers, then thermal warp characteristics are optimized and concave shape is maintained during reflow, but manufacturing complexity increases
Solution Approach 1:
The substrate is divided into multiple layers (top layers, bottom layers, and optional core layers) with distinct material removal patterns applied to each. This segmentation allows independent optimization of warp characteristics for different regions and layers, enabling precise control over thermal warp behavior during reflow while maintaining manageable manufacturing complexity through modular design.
Solution Approach 2:
Material is removed from specific patterns on top and bottom layers rather than uniformly across the entire substrate. This local quality approach targets specific regions where warp control is most critical, applying material removal only where needed to achieve the desired concave shape during reflow, thereby optimizing warp control without unnecessarily increasing overall manufacturing complexity.
2Reliability
If asymmetric thermomechanical properties are present in FC and BC layers, then electrical performance is optimized, but convex shape forms during reflow reducing chip joining yield
Solution Approach 1:
The invention deliberately introduces asymmetric material removal patterns on the top and bottom layers to counterbalance the inherent asymmetric thermomechanical properties of the FC and BC layers. This controlled asymmetry in material distribution compensates for the asymmetric thermal expansion differences, preventing the formation of convex shape during reflow and maintaining the desired concave configuration for optimal chip joining yield.
Solution Approach 2:
Material is removed from specific patterns on the layers before the reflow process occurs. This preliminary action preemptively counteracts the thermal warp that would otherwise occur during reflow, creating a pre-compensated substrate structure that maintains the correct concave shape during the heating process, thereby preventing convex formation and ensuring high chip joining yield.
3Ease of manufacture
If core is eliminated to reduce cost, then manufacturing cost decreases, but warp control becomes more difficult
Solution Approach 1:
When the core is eliminated to reduce cost, material is removed from specific patterns on the top and bottom layers in advance of the reflow process. This preliminary material removal creates a compensated structure that anticipates and counteracts the warp that would otherwise occur without the core's stabilizing presence, thereby maintaining precise warp control in the coreless substrate without increasing manufacturing complexity.
Solution Approach 2:
The invention changes the physical parameters of the coreless substrate by removing material from specific patterns on the top and bottom layers. This parameter modification alters the thermal mass distribution and stress profile of the substrate, enabling precise control over warp behavior during reflow even in the absence of a core, thereby maintaining manufacturing precision while benefiting from reduced manufacturing cost.
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 approach optimizes thermal warp characteristics, enhancing the yield of organic substrates by ensuring a concave shape during reflow, reducing connection failures, and meeting industry standards for both room temperature and reflow conditions.
Implementation Method 1
The removal of the material from one or more of the top layers and/or bottom layers changes a thermal warp of the organic substrate. Thermal warp is change in warp at given locations of a substrate for a given temperature change.
Data Source
AI summary
An organic substrate and method of making with optimal thermal warp characteristics is disclosed. The organic substrate has one or more top layers and one or more bottom layers. A chip footprint region is a surface region on each of the top and bottom layers that is defined as the projection of one or more semiconductor chips (chips) on the surface of each of the top and bottom layers. One or more top removal patterns are located on and may or may not remove material from the surface of one or more of the top layers within the chip footprint region of the respective top layer. One or more bottom removal patterns are located on and remove material from the surface of one or more of the bottom layers outside the chip footprint region of the respective bottom layer. The removal of the material from one or more of the top layers and/or bottom layers changes and optimizes a thermal warp of the organic substrate. In some embodiments, a Shape Inversion Temperature (SIT) of the substrate is made equal to or above a reflow temperature.