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www.us-
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February, 2020
Piezo Jet Valve Dispensing: Precise Dots at 1,500 Times Per Second
By Can La, Product Manager, Techcon S
electing the automated dispens- ing technology that is the best fit for a specific application
from the half-dozen or so familiar technologies available — such as the auger valve, progressive cavity pump, time-pressure valve or pneu- matic jet valve — is not a considera- tion to be made lightly. For most operations, the conse-
quent match is adequate, and attrib- utes such as throughput and quality are well-suited to the application on an ongoing basis. For others, howev- er, such as medium- to high-volume mobile device, LED, consumer elec- tronics, and medical device assem- blers, there is a constant drive for ever-higher yields and for an advanced dispensing technology that can better help them achieve it. For these users, there is a rela-
tively new technology that can increase dispensing rates for adhe- sives and other fluids by some 20 times or more — at rates as fast as 1,500 Hz continuously with up to 2,000 Hz maximum burst. This is the piezo actuated jet dispensing valve, which dispenses at approximately twice the speed of the pneumatic jet valve.
Operators are often amazed at
the impressive placement precision and small, neat dot sizes generated
by a piezo jet valve, especially consid- ering that it is moving so fast and that the material is being shot and not physically placed, as would be the case with most dispensing solu- tions that rely on actual contact with
0.5 nl, with outstanding consistency and repeatability. This precision also makes the piezo jet suitable for some other niche applications where speed is less of a factor, but where opera- tors have a challenging time achiev-
Piezo Jet Speed Jet valves — both the older
pneumatic jet technology and the newer piezo jet technology — gain a significant speed advantage, prima- rily by eliminating the z-axis of movement. While the height sensing and repositioning and the up/down motion that is necessary for contact- based valves, such as progressive pump and auger valve technologies, with the needle moving down to touch the substrate to dispense the fluid and then pull back up, are con- sidered reasonably fast by most crite- ria, these account for a high percent- age of the required dispensing time. Contactless jet dispensing, by
contrast, shoots the material accu- rately from a fixed location above the substrate, shot after shot. This enables the pneumatic jet valve to reclaim this excess motion time and dispense at speeds some 10 times faster than contact-based valves. However, while the pneumatic
Diagram of a piezo jet dispensing system.
the substrate. Using sophisticated controllers, shot sizes can be achieved as small as
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ing the desired dispensing of ultra- small dots or ultra-thin lines consis- tently over time.
jet valve technology leaves the speed enhancement at “only” 1,000 percent, the piezo jet valve ups the ante con- siderably. In these devices, rather than relying upon air pressure, a piezoelectric actuator converts an electrical signal into a highly precise motion that dispenses the material
Continued on page 90
See at IPC APEX, Booth 1202, and at ATX / MD&M West, Booth 729
See at IPC APEX, Booth 3802, at ATX / MD&M West, Booth 1747, and at SPIE Photonics West, Booth 4360
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