Stencil Spot Cleaner Assembly for Solder Paste Removal
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Solution Overview
Problem
Existing stencil printers face issues with excess solder paste accumulation on the stencil's underside, leading to unintended deposition on circuit boards and alignment complications, which are not effectively addressed by traditional cleaning methods.
Innovation Solution
A stencil printer with a spot cleaner assembly that moves in an x-axis direction, equipped with a cleaning head featuring replaceable media, a solvent dispensing system, and a vacuum system, allowing for precise and targeted removal of solder paste and flux residue from the stencil's bottom surface, along with a controller to manage the cleaning path and operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional stencil wiper system is used to clean the bottom of the stencil, then the entire underside of the stencil is cleaned, but the system is complex and requires continuous paper supply and vacuum operations
Solution Approach 1:
The invention extracts only the necessary cleaning function from the complex traditional system. Instead of using a continuous paper supply and vacuum system, the patent employs a simple disposable sponge that is applied directly to the stencil bottom surface and then discarded. This extraction of the essential cleaning function eliminates the complexity of paper handling, vacuum plenums, and solvent delivery systems while maintaining effective stencil cleaning.
Solution Approach 2:
The invention uses a disposable sponge as the cleaning medium. The sponge is applied to the bottom of the stencil, performs the cleaning function, and is then discarded. This eliminates the need for complex reusable cleaning systems, paper supply mechanisms, and vacuum operations. The disposable nature of the sponge simplifies the entire cleaning system while maintaining reliable cleaning effectiveness.
2Reliability
If the stencil wiper blade assembly moves along the entire stencil, then complete cleaning is achieved, but cleaning time and productivity are reduced
Solution Approach 1:
The invention applies local quality by focusing the cleaning action only on specific areas where solder paste accumulation occurs, rather than cleaning the entire stencil surface. The disposable sponge is positioned to contact only the bottom surface of the stencil where excess paste accumulates, providing targeted cleaning that maintains completeness where needed while leaving uncontaminated areas unchanged, thereby reducing cleaning time.
Solution Approach 2:
The invention uses partial action by applying the sponge only to the portions of the stencil bottom surface that require cleaning. Instead of moving the wiper blade assembly along the entire stencil length, the sponge is applied locally to areas with solder paste accumulation. This partial cleaning approach maintains cleaning effectiveness for the problematic areas while significantly reducing the time required compared to comprehensive cleaning of the entire stencil surface.
3Reliability
If solvent is continuously applied to the stencil, then solder paste removal is effective, but solvent waste and environmental impact increase
Solution Approach 1:
The invention eliminates continuous solvent application by using a disposable sponge that physically absorbs and removes solder paste through mechanical action. The sponge is applied to the stencil bottom, absorbs excess paste, and is then discarded. This eliminates the need for continuous solvent delivery systems, reducing solvent waste and environmental impact while maintaining effective solder paste removal.
Solution Approach 2:
The invention extracts the solvent delivery system from the cleaning process. Instead of continuously applying solvent through a complex delivery network, the patent uses a simple disposable sponge that performs the cleaning function through physical absorption and mechanical removal. This extraction of the solvent delivery function eliminates solvent waste while maintaining effective solder paste removal.
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 solution effectively removes excess solder paste and flux residue, reducing circuit board defects and improving stencil cleaning efficiency, thereby enhancing productivity by minimizing the frequency of cleaning and post-inspection requirements.
Implementation Method 1
a vacuum system, allowing for precise and targeted removal of solder paste and flux residue from the stencil's bottom surface
Implementation Method 2
a solvent dispensing system, and a vacuum system, allowing for precise and targeted removal of solder paste and flux residue from the stencil's bottom surface
Data Source
AI summary
A stencil printer includes a stencil having a top surface and a bottom surface, a material applicator to apply material on the top surface of the stencil, and a stencil wiper assembly to clean the bottom surface of the stencil in a y-axis direction. The stencil wiper assembly has a wiper blade assembly configured to engage the bottom surface of the stencil and wipe the bottom surface of the stencil when moving the stencil wiper blade assembly along a stencil wiper gantry. The stencil wiper assembly further includes a spot cleaner assembly movably secured to the stencil wiper assembly. The spot cleaner assembly is configured to move in an x-axis direction and to spot clean the bottom of the stencil. A method for spot cleaning a stencil is further disclosed.