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Assembly and Production
Process Improvements in Fluid Dispensing By Dan Ashley, Nordson ASYMTEK, Carlsbad, CA J
etting is the fluid dispensing process where fluid is rapidly ejected through a nozzle and
uses the fluid momentum to break free from the nozzle. Jet dispensing has been available in the electronics manufacturing industry since 1993 when jetting technology was first introduced by Nordson ASYMTEK. At the time, it was a revolutionary concept, as fluid dispensing was only being done using a needle that required an up-and-down z-axis motion to dispense the fluid. With the jet, a discrete volume of material is ejected with each jet shot. Jetting greatly increases dispensing speed because z-axis movement isn’t need- ed to overcome fluid cohesion as is required with needle dispensing. When traveling from one dis-
pense location to the next, jetting is done on-the-fly. High flow rates are achieved, fluid is deposited in tight places with much smaller keep-out areas, and the ability to use a wide
of the jet itself along with the accom- panying software, and adding wire- less capabilities. Nordson ASYMTEK introduced the patent-pending Nex - Jet™ system which consists of a dis-
the NexJet has a high actuation fre- quency of 300Hz. High actuation fre- quency means that more dots can be delivered in a period of time. In this case, the jet can deliver 300 shots of fluid in one second, an improve- ment of 50 percent to help increase units per hour (UPH). An additional impediment
Genius jet cartridge cleaner.
pense platform, the NexJet actuator, and incorporates the patent-pending Genius™ Jet Cartridge. This car- tridge is one piece and is easily removed and replaced without tools. It fits in the palm of one’s hand. It contains the fluid and is the only wetted part of the jetted mechanism. An RFID usage tracking system imparts a “smart” feature to the jet cartridge. The NexJet accommodates a wide breadth of fluids, applica- tions, and manufacturing for emerg- ing technologies such as stacked die, precision coating, LEDs, flat panel displays, lab-on-a-chip, MEMS pack- aging, and others.
Increased Speed and Throughput
Speed and throughput have Other jet parts (left) vs. Genius jet cartridge (right).
range of fluids that are deposited in a vast number of configurations allows for flexibility. Thousands of jets are used in production today.
increased exponentially over the years, yet they are still factors chal- lenging the existing dispensing sys- tems as fast never seems to be fast enough.
However, increasing through put
involves more than just speeding up the actual act of dispensing. Factors that contribute to throughput include conveying and heating the parts, the vision and/or imaging system, and the
A new generation of fluid jetting dispensing has emerged, offering faster operation, less downtime and easier, and less costly maintenance.
At NEPCON China last April, a
new concept in jet dispensing was introduced. Once again, it is a signif- icant change in dispensing technolo- gy, revolutionizing the construction
height sensing, which can ensure con- sistent dispensing results. Improvements are constantly
being made to these aspects of the dis- pensing process as well. For example,
to speed and throughput is the time required to change and clean the parts of the dispense needle or jet valve. The fluids are often messy, sticky, and dif- ficult to clean. Cleaning is labor- intensive, fluid is often wasted in the process, and production has to be stopped so the valve can be removed, have its parts cleaned, and be replaced, or have the valve removed and replaced by a back-up clean valve. There are many compo-
nents to a jetting system. To clean the jet, the entire actuator (or driver) and each piece of the jet must be removed, cleaned, inspected, and replaced. Jets can have as many as 8 to 14 pieces. These parts can include seals, o-rings, seats, nozzles, and nee- dles, and sometimes these parts have parts that have to be disassembled, cleaned, and inspected. All these parts come in con- tact with fluid. It can be a hassle and barrier to high yields if equipment opera- tors have to know how to disassemble and reassem- ble all these pieces correct- ly. Down-time is increased if one of the pieces is lost or one of the parts in the system fails or wears out. For contract manufactur- ers or companies that need to change fluids frequent- ly, this creates a bottleneck or requires the purchase of additional jets to be kept on the shelf and changed out while others are being cleaned.
One Part to Clean One thing that makes the
NexJet system so revolutionary is that in its jetting mechanism there is only one small part that contains fluid and which has to be changed and cleaned. The actuator remains on the dispensing robot. Only the Genius Jet Cartridge needs to be removed, and this can be done with- out any tools. Each NexJet system
comes with two cartridges, so when one is removed to be cleaned or dis- posed of, the other can be immediate- ly placed in service. To remove the cartridge, the operator simply lifts a lever and squeezes two tabs to release the cartridge from the actua- tor; the old cartridge is removed from the heater unit and a clean cartridge installed; the retainer tabs are squeezed together and the heater unit is returned to the actuator; the lever is pushed down; and the system is ready to jet. Change-over time is about 30 seconds. Each jet comes with a specially designed off-line cleaning and inspection tool that flushes the jet cartridge, tests the nozzle seal, and provides visual veri- fication that the jet cartridge is clean. No cartridge disassembly or reassembly is required. Extra car- tridges are small and easy to store to have ready when needed.
RFID Plays a Part Wireless communication takes
the NexJet to the next level. An
July, 2012
Genius jet cartridge.
RFID transceiver is embedded in the dispense system to communicate with the stored memory on the Genius Jet Cartridge. The number of cycles is wirelessly communicated and the software is programmed to warn the operator when the limit is reached. Custom messages can be written and saved to the jet cartridge and then relayed to the jetting recipe. Once again the operator receives a warning if recipe parame- ters are not met. The system ensures that the cor-
rect cartridge is installed, checks to see if the cartridge is within life
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