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equipment industry
rhombus4
Tightly wrapped
Tube heaters are applied any time where liquid or gaseous media are being
delivered through tubes. These tube heaters do have a critical impact on process
results when used with thermal sensitive media or processes and contribute to the
extension of maintenance cycles in the facility. Pump and gas line heaters, were
developed especially for those kinds of applications. By Matthias Müller of Watlow.
T
he well tempered process the tubing is, in such cases essential which negatively affect the results of
heating and tempering of for good process results. The the process which is run under clean
media plays an important role in following example emphasizes the room conditions. Moreover, these
modern process engineering as many importance of tube heating for precipitations cause unscheduled
processes only proceed within a thermally critical processes: maintenance cycles which generate
specific temperature range. Since significant cost due to equipment
raw material is generally delivered to The pictures below show exhaust downtime. Use of conventional
the process chamber through tubing lines of an aluminium etching tool as heated cable may not prevent
systems and reaction products are it is used in semiconductor precipitation because a full coverage
removed through tubing systems as fabrication. On the left picture a tube of the tube and thus uniform
well, it is necessary to hold delivery with insufficient heating of the tubing tempering cannot be achieved.
and exhaust lines at a certain is shown, whereas the right picture
temperature. shows a fully heated tube. In this Therefore, for this kind of application
process, formation of aluminium a heating system was developed
The smaller the temperature window chloride, which precipitates along the which ensures a full coverage of the
in which the processes take place, walls of the tubing, is critical. These tubing and also uniform tempering.
the more important becomes the precipitations lead to a successive The heating elements are applicable
right tempering of the tubing. reduction of the cross section of the at temperatures up to 200°C and are
Precise temperature control along tube and are sources for particles available for different nominal
Left: Fig. 1:
Illustrates the
reduction in
tube cross
section due to
aluminum
chloride build
up in an
insufficiently
heated tube
Far left: Fig. 2:
Fully heated
tube shows no
build up of
precipitate
September 2009 www.compoundsemiconductor.net 27
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