Dispensing and MID (Molded Interconnected Devices) technologies are
developing rapidly. Current technology drivers are LED and communication
products. On September 28th, Essemtec’s technology day focused on new
developments and future challenges. The event was free of charge for all
Essemtec is the leading manufacturer of
production systems for electronics. It is the only supplier that can
deliver machines, processes and knowhow from one source: dispensers,
printers, pick-and-place machines, ovens, storage and handling systems.
year, Essemtec organizes a technology day at its headquarters in Aesch,
Switzerland. Participants from Switzerland, Germany and Austria attend
the event, which is free of charge. The aim is to present information
about new technologies, processes, machines and applications. This year
the main themes were dispensing and 3D-MIDs.
Thixotropy Is Not Shear Thinning
number of applications for jet valves is growing rapidly, especially
for LED manufacturing and production. Juergen Staettler, CEO of Vermes
Microdispensing GmbH (a subsidiary of the Essemtec Group), knows the
reason for this development. Casting LEDs with filled media requires
flexibility, accuracy and speed that currently can be achieved only by
piezo jet valves.
Vermes offers two types of valves that differ
in the application of force to the dispense media. High viscosity fluids
require the direct high force of the piezo. Typically, these valves are
considered open. For low viscosity fluids, closed valves generally are
Selecting the right valve, the correct nozzle and the
appropriate valve timing is a demanding task. The process engineer must
not only know the required cycle time but also must have a lot of
information about the medium rheology and the application. Rheology
includes many properties such as the viscosity, thread formation,
temperature and fillers. The process engineer also strongly
distinguishes between shear thinning (no structure rebuilding at rest)
and thixotropy (rebuilding of structure at rest).
The speed of a
jet valve is limited due to self-heating of the piezo. 500 Hz is a high
frequency for a piezo jet valve and 1000 Hz can be achieved only for a
short period. Reaching the required cycle time requires long-term
experience. Vermes currently is developing a new technology that soon
will break the current limitations.
New Dispensing Machines from Essemtec
valves can be installed on the new Scorpion dispensing machine and the
new Paraquda pick-and-place machines from Essemtec. These machines
feature an innovative valve quick-change system. Due to the very high
speed and accuracy, these machines are well prepared for future
The Scorpion, a pure dispensing machine, is used
for all types of dot, line and curve dispensing. Automatic calibration
systems for height, viscosity and needle are included. A combined
dispensing and placement machine such as the Paraquda is suggested for
applications including paste adding, glue dot dispensing for some
components or electronics prototyping.
LDS Technology for MID
Baecker from LPKF Laser & Electronics AG informed the group about
the interesting development in MID technologies. LDS Laser Direct
Structuring, a technology developed by LPKF, is no longer used only for
prototypes. There are many new volume products such as antennas for
communication devices, automotive and medical applications.
concept of LDS is brilliantly simple. A product is made from an LDS
polymer or coated with an LDS paint. The laser then roughs (activates)
the areas where copper will be built up in a subsequent chemical
process. The roughness of the surface ensures excellent adhesion of
copper and the work piece. Layout changes only require reprogramming the
laser and no tooling costs, making this process very flexible.
3D-MID Creates New Design Rules
types of LDS polymers are available for different applications. Even
solderable high-temperature thermoplastics exist. It is even possible to
create vias in LDS technology. Either the laser burns the required via
itself or it activates the surface inside the hole. However, layout
designers must become familiar with a couple of new design rules.
circuits should be rounded rather than angled so that the laser can
activate them with continuous speed. Furthermore, there is a 70° rule: A
vertical surface (90°) cannot be activated by the laser. But if a
surface is in an angle of 70°, then the laser can selectively activate
it without having to turn the work piece.
The World’s First Standard Machine for 3-D Placement And Dispensing
allows the application of circuits directly to housing parts.
Therefore, MIDs are usually in 3-D. In 2011, Essemtec introduced Hydra,
the first standard machine for the assembly of such products. It is a
combination of a Paraquda pick-and-place with a 6 axes robot. Hydra
dispenses glue and paste and it places components at almost any angle.
Despite the complex process, the machine’s operation is as simple as
with a 2-D pick-and-place machine.
Hydra places all types of SMD
components. In 3-D mode, the 4-nozzle pick-and-place head can place up
to 2,500 components per hour. In 2-D mode the placement rate can reach
up to 7,000 cph. The machine can be installed in a production line and
changeover between products can be very fast. Therefore, Hydra can
assemble prototypes as well as series.