Intermediate-Substrate Solder Paste Printing for Precise PCB Deposition
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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 issues, blade angle optimization, and high viscosity of solder paste, leading to defects like solder bridges and insufficient solder application, which are not effectively addressed by existing jetting and screen-printing methods.
Innovation Solution
A two-step printing system segregates the jetting and application processes, using an initial printing on an intermediate substrate followed by a high-resolution, low-debris transfer to a final substrate, employing imaging systems for control and a laser-based system for precise deposition, allowing for uniform layer creation and precise material transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screen-printing is used to print solder paste, then the printing process can be performed, but defects such as solder bridges and insufficient solder application occur due to stencil accuracy issues and blade angle optimization problems
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 eliminates the need for physical contact between blade/squeegee and stencil, removing the sources of mechanical error (blade angle, pressure, stencil thickness variations) that cause printing defects. The jet printing system achieves precise solder paste deposition through controlled material ejection, significantly improving manufacturing precision while maintaining reliability.
2Productivity
If printing speed is increased to improve productivity, then more solder paste can be applied faster, but insufficient solder is applied because less time is spent in applying the solder paste through the stencil aperture surface
Solution Approach 1:
The jet printing system replaces the time-dependent mechanical screening process with a controlled ejection process. In screen-printing, higher speeds reduce the time for paste to be forced through apertures, leading to incomplete application. The jet printing system directly ejects material through apertures without requiring prolonged contact time, allowing high printing speeds to be achieved without compromising solder paste application completeness. This mechanical substitution decouples printing speed from application quality.
3Ease of operation
If jet printing is used to print viscous solder paste, then printing can be performed without stencil contact, but the high viscosity of solder paste causes jetting complications and clogging since most jetting heads are designed for low viscosity materials
Solution Approach 1:
The patent modifies the jet printing system parameters to accommodate high viscosity materials. Instead of using conventional jetting heads designed for low viscosity materials, the system employs specialized jetting technology with adjusted pressure, aperture size, and material delivery parameters. This parameter optimization enables effective jetting of viscous solder paste without clogging, resolving the contradiction between operational simplicity and device complexity by tailoring the system parameters to the specific material properties.
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 and improved accuracy, addressing the limitations of traditional methods by ensuring precise control and uniformity throughout the printing process.
Implementation Method 1
a subsequent transferring of the printed viscous material from the film to a substrate is performed by 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.