Side-Exposed Embedded Trace Substrate for Reliable Soldering
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Solution Overview
Problem
Conventional embedded trace substrates face issues with poor welding reliability due to insufficient contact area with solder and inadequate packaging material filling, primarily because they have only one side in contact with solder and a small gap between devices and pads during packaging.
Innovation Solution
A side-exposed embedded trace substrate is developed, featuring grooves on the pads of the first wiring layer embedded in the dielectric layer to increase the side-exposed area, enhancing contact with solder and creating a larger gap for better packaging material flow, which is achieved through a manufacturing method involving etching and resist layer processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pad is fully embedded in the dielectric layer, then the wiring integration is improved, but the contact area with solder is insufficient
Solution Approach 1:
The invention transitions from a single-sided contact configuration to a multi-dimensional contact configuration by creating grooves that expose the pad on the side surface. This allows the pad to contact solder not only from the top but also from the sides, effectively increasing the contact area and improving welding reliability while maintaining the embedded wiring structure.
Solution Approach 2:
The groove structure creates a porous-like configuration in the dielectric layer, allowing solder to access the pad from multiple directions. The groove acts as a channel that enables solder flow and contact with the pad side surface, thereby enhancing the welding interface without compromising the embedded trace structure.
2Device complexity
If the pad is fully embedded in the dielectric layer, then the wiring integration is improved, but the packaging material filling is insufficient
Solution Approach 1:
The groove structure opens up a new dimensional space for packaging material to flow into. By creating a side exposure through the groove, the packaging material can access the gap between the device and pad from the side direction, ensuring sufficient filling that would be difficult to achieve with a fully embedded configuration.
3Reliability
If grooves are added to the pad, then the contact area with solder is increased, but the manufacturing complexity is increased
Solution Approach 1:
The manufacturing process is segmented into distinct stages: forming the groove structure first, then subsequently forming the pad within the groove. This segmentation allows each step to be optimized independently and simplifies the overall manufacturing complexity by breaking down the complex groove-pad formation into manageable sequential operations.
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 side-exposed embedded trace substrate improves welding reliability by increasing the contact area with solder and ensures sufficient packaging material filling, addressing the limitations of traditional embedded trace substrates.
Implementation Method 1
the process of etching is selected from acid etching or alkaline etching
Implementation Method 2
the process of etching is selected from acid etching or alkaline etching
Implementation Method 3
forming a first sub-layer of the first wiring layer in the second opening by electroplating
Implementation Method 4
applying a first resist layer on the substrate, and forming a first opening by exposure and development
Data Source
AI summary
A side-exposed embedded trace substrate includes a dielectric layer, a first wiring layer and a first wiring layer embedded in the dielectric layer. An outer surface of the first wiring layer is not higher than a surface of the dielectric layer, and the first wiring layer includes a pad having a groove to increase a side-exposed area of the pad. The contact area between the substrate and the solder during package welding is increased so that the welding reliability is enhanced, the problem of poor welding or poor reliability caused by trace embedding may be avoided, and poor filling of the packaging material due to insufficient gap between the device and the pad during packaging may be prevented.