Thermal Conductor Covering Conductive Bumps for Solder Reflow Wetting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The issue of non-wetting of solder bumps during the reflow process in conventional semiconductor packaging due to ineffective heat transfer from the upper protective film to the lower solder bumps, leading to connectivity issues.
Innovation Solution
The use of a thermal conductor composed of a first thermal conductive material covering conductive bumps and a second thermal conductive material with higher thermal conductivity, surrounded by a softer first material, to enhance heat transfer and prevent non-wetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed on the conductive bumps to protect them, then the protective function is improved, but the thermal conduction efficiency deteriorates because the heat source cannot be effectively transferred to the solder bumps
Solution Approach 1:
The protective film is segmented into two distinct layers: a lower protective film layer (first protective film layer) that provides mechanical protection to the conductive bump, and an upper heat transfer layer (second protective film layer) that facilitates thermal conduction. This segmentation allows each layer to specialize in its respective function without compromising the other.
Solution Approach 2:
Different regions of the protective film structure are assigned different material properties: the lower layer adjacent to the conductive bump uses a material optimized for protection and thermal conduction, while the upper layer uses a material optimized for heat transfer from the heat source. This local differentiation of material properties resolves the contradiction between protection and thermal efficiency.
2Ease of manufacture
If the heat source is deposited on the upper protective film during reflow heating, then the heating process is simplified, but the heat cannot be effectively transferred to the lower solder bumps causing non-wetting
Solution Approach 1:
The upper protective film layer acts as an intermediary medium that facilitates heat transfer from the heat source to the lower protective film layer and subsequently to the solder bumps. This intermediary layer ensures efficient thermal coupling without requiring direct contact between the heat source and the solder bumps, thereby maintaining solder wetting quality while preserving manufacturing simplicity.
Solution Approach 2:
The protective film is constructed as a composite structure with two layers having different thermal conductivities and material properties. The upper layer is designed with higher thermal conductivity to efficiently conduct heat from the heat source, while the lower layer provides protection and interfaces with the solder bumps. This composite structure simultaneously achieves effective heat transfer and reliable solder wetting.
3Device complexity
If a single-layer protective film is used to protect conductive bumps, then the structure is simple, but the thermal conduction efficiency is insufficient
Solution Approach 1:
The protective film is divided into two functional layers with distinct roles: the lower layer provides mechanical protection and interfaces with the conductive bump, while the upper layer is optimized for heat transfer. This segmentation enables the structure to achieve superior thermal conduction efficiency compared to a single-layer film, while maintaining reasonable structural complexity.
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
Improves thermal conduction efficiency and prevents solder non-wetting, while providing buffer protection for the conductive bumps, enhancing product yield and connectivity.
Implementation Method 1
a second thermal conductive material adjacent to the first thermal conductive material, wherein a thermal conductivity of the second thermal conductive material is greater than a thermal conductivity of the first thermal conductive material
Data Source
AI summary
An electronic package and a manufacturing method thereof are provided, where the manufacturing method is to dispose an electronic structure with a plurality of conductive bumps and a thermal conductor on its upper surface on a carrier structure via external bumps on its lower surface, so that when reflowing the external bumps, the heat of the heat source joint is conducted from the upper surface of the electronic structure to the external bumps on the lower surface via the thermal conductor, so as to facilitate the heating and reflowing of the external bumps to avoid the problem of non-wetting of the solder.