Lift Tool Assembly Decoupling for Stencil Printer Substrate Alignment
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Solution Overview
Problem
Current stencil printing systems face challenges in reducing cycle time while maintaining quality, particularly in aligning and clamping electronic substrates during the printing process, which affects the precision and consistency of solder paste application on printed circuit boards.
Innovation Solution
The introduction of a lift tool assembly with a modular clamping subassembly and a decoupled lift tool system that operates independently of the transport rail members, allowing for precise positioning and clamping of substrates at different heights, including a vision system clearance and print height, to enhance alignment and application precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the lift tool assembly is integrated with the transport rail members, then the system structure is simpler, but the positioning precision and alignment accuracy are reduced
Solution Approach 1:
The system is divided into separate functional modules: the transport rail members handle substrate transport, while the lift tool assembly handles precise vertical positioning and clamping. This segmentation allows each module to be optimized independently for its specific function, improving overall positioning precision without requiring complete system redesign.
Solution Approach 2:
The lift tool assembly acts as an intermediary between the transport rail members and the stencil printing system. It provides a decoupled interface that translates transport movements into precise printing positions, enabling high-precision alignment while maintaining system modularity and reducing direct mechanical coupling.
2Productivity
If the cycle time is reduced for higher productivity, then more circuit boards can be produced, but the quality consistency and alignment precision may deteriorate
Solution Approach 1:
The lift tool assembly performs preliminary positioning and clamping of the substrate before the printing operation begins. Fiducial alignment and substrate securing are completed in advance, allowing the main printing process to proceed quickly without compromising precision. This preliminary preparation enables fast cycle times while maintaining consistent alignment quality.
Solution Approach 2:
The system replaces complex mechanical alignment mechanisms with a combination of vision system guidance and precision lift tool positioning. This substitution allows for rapid, automated alignment with high precision, reducing the time required for manual or mechanically-intensive alignment procedures while maintaining quality consistency.
3Stability of the object's composition
If the clamping force is increased to secure the substrate, then the substrate positioning stability improves, but the risk of substrate damage or deformation increases
Solution Approach 1:
The clamping force is applied locally at specific clamping points rather than uniformly across the entire substrate. The lift tool assembly uses distributed clamping elements that apply force only where needed to secure the substrate edges, providing sufficient positioning stability while minimizing the risk of damage to the substrate surface and components.
Solution Approach 2:
The clamping mechanism in the lift tool assembly is designed to be dynamically adjustable, allowing the clamping force to be optimized for each substrate type and thickness. The system can adapt the clamping pressure to provide just enough force for stable positioning without excessive force that could cause damage, responding to real-time positioning requirements.
Data Source
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AI summary
A stencil printer (10) includes a frame (12), a stencil coupled to the frame, and a print head (20) coupled to the frame to deposit and print viscous material over the stencil. The stencil printer further includes a lift table assembly (22) configured to support the substrate (16) in a transport position and a print position, and a conveyor system (14). The conveyor system includes a pair of rail members (28, 30) coupled to the frame. The pair of rail members extends through the frame and is configured to transport the substrate through the stencil printer. The conveyor system further includes, for each rail member (28, 30), a lift tool assembly (32) coupled to the rail member. The lift tool assembly (32) is configured to cooperate with the lift table assembly (22) and to engage and support the substrate (16) at a transport height and a print height.