Nano-Coated Solder Paste Stencil for Fine-Pitch Aperture Release
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional solder paste stencils face issues with insufficient solder paste deposition and aperture clogging, leading to solder bridging and defects in fine pitch ball grid array (BGA) surface-mount technology (SMT) processes, despite attempts to reduce aperture size.
Innovation Solution
A smooth nano-coating on the aperture walls of the solder paste stencil using physical vapor deposition (PVD) is applied to reduce solder paste wetting, ensuring maximum coverage and improved release capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aperture size is reduced to reduce solder paste volume, then solder bridging is prevented, but insufficient solder paste deposition and aperture clogging occur
Solution Approach 1:
The patent applies a hydrophobic coating to the aperture walls, changing the surface energy parameters of the aperture interior. This parameter change allows the aperture to maintain smaller dimensions while preventing solder paste adhesion, thereby resolving the contradiction between preventing solder bridging and ensuring sufficient solder paste deposition
Solution Approach 2:
The hydrophobic coating acts as an intermediary layer between the solder paste and the aperture wall. This intermediary prevents direct interaction between the solder paste and the aperture surface, enabling reduced aperture sizes without causing clogging or insufficient deposition
2Object-affected harmful factors
If aperture size is reduced to reduce solder paste volume, then solder bridging is prevented, but aperture clogging occurs
Solution Approach 1:
By modifying the surface energy parameters of the aperture walls through hydrophobic coating, the patent enables smaller aperture sizes to function reliably without clogging, thus resolving the contradiction between preventing solder bridging and maintaining aperture reliability
Solution Approach 2:
The hydrophobic coating serves as an intermediary that prevents solder paste from adhering to aperture walls, allowing reduced aperture sizes to operate without clogging while still preventing solder bridging
3Ease of manufacture
If conventional coating techniques (wipe-on or spray deposition) are used on aperture walls, then some coverage is achieved, but maximum coverage is not ensured especially for fine pitch apertures
Solution Approach 1:
The patent replaces mechanical coating methods (wipe-on or spray deposition) with a chemical vapor deposition process. This substitution enables uniform hydrophobic coating coverage on fine pitch apertures that cannot be achieved through conventional mechanical means
Solution Approach 2:
The patent introduces a chemical vapor deposition process as an intermediary method to achieve uniform coating coverage. This intermediary process ensures maximum hydrophobic coating coverage on aperture walls, particularly for fine pitch apertures where conventional methods fail
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 PVD nano-coating significantly enhances solder paste release, preventing solder bridging and defects by maintaining high hydrophobicity and coating durability, even after numerous printing cycles, thereby improving the overall SMT process.
Implementation Method 1
a precise nano-coating via physical vapor deposition (PVD) was developed to improve the solder paste release capability
Implementation Method 2
each aperture wall of each of the plurality of solder apertures is coated with a coating material that reduces the wetting of a solder paste relative to the stencil aperture walls
Data Source
AI summary
A solder paste stencil includes, in one embodiment, a substrate defining solder apertures, each aperture wall of each of the solder apertures is coated with a coating material that reduces wetting of a solder paste relative to the aperture walls.