Jet Dispensing Ejector Piston Displacement Control
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Solution Overview
Problem
Existing methods for jetting viscous media onto substrates, such as solder paste or adhesive, face challenges in achieving high production accuracy and reliability due to variations in deposit volume and shape, leading to issues like dry joints or short-circuits, which are not adequately addressed by current ejector technologies.
Innovation Solution
A system with a freely moving piston controlled by voltage and current, allowing for closed-loop compensation of variations in the jetting process, and an open connection to the feeder channel for continuous flow, enabling precise control of the reciprocating movement and media displacement, ensuring consistent droplet formation and placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional ejectors with valves and seats are used to control jetting, then the jetting process can be controlled, but variations in hardware and media rheology lead to unwanted variations in returning position and stroke length, reducing manufacturing precision
Solution Approach 1:
The patent implements a freely moving piston without mechanical stops or valve seats, allowing the piston to dynamically adjust its returning position based on real-time feedback from displacement sensors. This dynamic configuration enables the system to adapt to variations in media rheology and hardware tolerances, maintaining consistent droplet volume and shape across different operating conditions.
Solution Approach 2:
The system incorporates displacement sensors that continuously monitor the piston's position and stroke length, feeding this information back to the control system. The controller adjusts the voltage and current applied to the piezoelectric actuator based on this feedback, compensating for variations in media properties and ensuring repeatable jetting performance.
2Manufacturing precision
If closed-loop control with displacement monitoring is implemented, then manufacturing precision and reliability are improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical valve and seat mechanisms with a freely moving piston actuated by piezoelectric elements. This substitution eliminates the need for precision-machined valve seats and complex timing mechanisms, reducing mechanical complexity while maintaining control through electrical actuation and electronic feedback.
Solution Approach 2:
The system controls jetting parameters by adjusting voltage and current applied to the piezoelectric actuator rather than through complex mechanical adjustments. This electrical parameter control simplifies the system compared to mechanical adjustment mechanisms, allowing precise control of piston displacement and droplet formation through electronic signals.
3Quantity of substance
If larger volumes of viscous medium are jetted to compensate for under-deposition, then deposit volume increases, but the shape and positioning accuracy deteriorates
Solution Approach 1:
The system uses periodic reciprocating motion of the piston to jet multiple controlled droplets that build up the desired deposit volume. Each reciprocating stroke delivers a precisely controlled droplet, and by applying multiple strokes, the system accumulates the required volume while maintaining consistent droplet shape and position, avoiding the shape distortion that would result from jetting a single large volume.
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 solution enhances the reliability and accuracy of the jetting process, reducing the need for downstream inspections and allowing for real-time correction of printing errors, thereby improving the quality and reducing production costs by maintaining a process window for optimal jetting quality and performance.
Implementation Method 1
an impacting device including a piezoelectric actuator and a plunger operatively connected to the piezoelectric actuator
Implementation Method 2
a sensor configured to output a signal carrying a sensor parameter reflecting a displacement of the impacting device
Data Source
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AI summary
A method for jetting a viscous medium onto a substrate (23) is disclosed. The method comprises providing (110) viscous medium to a jetting chamber (5) of an ejector (1), operating (120) an impacting device (6, 7) to impact a volume of the viscous medium in the chamber such that viscous medium is jetted through a nozzle (4), connected to the chamber, towards the substrate, and monitoring (130) a displacement of the impacting device during the impact. An ejector and a system comprising such an ejector and a control unit (32) is also disclosed. The monitoring of the displacement allows for the operation of the impacting device to be controlled accordingly, thereby providing for an improved control of the jetting process.