Methods for printing solder paste and other viscous materials at high resolution
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Solution Overview
Problem
Current surface mount technology for printing solder paste on printed circuit boards faces challenges such as stencil accuracy, printing speed limitations, and clogging issues with jetting heads due to the viscous nature of solder paste, leading to defects in the final assembly.
Innovation Solution
A two-step printing system segregates the jetting process from the application process, using an initial printing on an intermediate substrate followed by a high-resolution, low-debris transfer to a final substrate, employing laser-assisted deposition and imaging systems to ensure accurate and uniform application of solder paste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If screen printing through stencil is used to apply solder paste, then the printing process can be performed, but printing speed is limited and stencil accuracy issues cause defects
Solution Approach 1:
The patent replaces the mechanical screen printing system with a jet printing system that uses controlled material ejection through apertures. This substitution enables higher printing speeds while maintaining precision through digital control of the jetting process, eliminating the mechanical limitations of stencil-based screen printing.
Solution Approach 2:
The patent changes the printing parameters by using jet printing technology that can dynamically control material flow rates, aperture sizes, and printing speeds. This allows optimization of both speed and precision independently, overcoming the fixed parameter constraints of traditional screen printing where stencil thickness and aperture size are fixed.
2Productivity
If jet printing is used to print viscous solder paste, then printing speed can be increased, but jetting heads clog due to the viscous nature of the material
Solution Approach 1:
The patent changes the physical parameters of the solder paste by reducing its viscosity through temperature control and compositional adjustments. This enables the material to flow smoothly through jet printing heads at high speeds without clogging, while still maintaining the necessary tackiness for proper solder application.
Solution Approach 2:
The patent implements periodic cleaning and maintenance cycles for the jetting heads, using ultrasonic vibration or pneumatic clearing mechanisms to prevent and remove any material buildup. This periodic action ensures continuous reliable operation at high printing speeds without jetting head clogging.
3Device complexity
If conventional screen printing is used, then the process is simple, but printing resolution is insufficient for high-precision applications
Solution Approach 1:
The patent segments the printing process into multiple independent jetting nozzles, each capable of precise material deposition. This segmentation allows for higher resolution by controlling individual nozzle output, while the modular architecture keeps the overall system complexity manageable through standardized components.
Solution Approach 2:
The patent replaces the mechanical stencil and squeegee system with a digitally controlled jet printing system. This substitution achieves higher printing resolution through precise digital control of material ejection, while the software-based control system manages complexity more efficiently than mechanical adjustments.
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 enables high-resolution, high-speed printing of viscous materials like solder paste with reduced defects, improving the precision and efficiency of the surface mount assembly process.
Implementation Method 1
a laser assisted deposition/laser dispensing system
Data Source
AI summary
Systems and methods in which dot-like portions of a material (e.g., a viscous material such as a solder paste) are printed or otherwise transferred onto an intermediate substrate at a first printing unit, the intermediate substrate having the dot-like portions of material printed thereon is transferred to a second printing unit, and the dot-like portions of material are transferred from the intermediate substrate to a final substrate at the second printing unit. Optionally, the first printing unit includes a coating system that creates a uniform layer of the material on a donor substrate, and the material is transferred in the individual dot-like portions from the donor substrate onto the intermediate substrate at the first printing unit. Each of the first and second printing units may employ a variety of printing or other transfer technologies. The system may also include material curing and imaging units to aid in the overall process.