FIELD OF THE INVENTION
The present invention relates to an improved process of in-situ joining of
damaged endless stainless steel belts or making new for transporting wafer
carrier into a vacuum deposition chamber.
BACKGROUND OF THE INVENTION
Vacuum chambers are used for various processes in solar cell manufacturing
industries. Some of the processes require in-line deposition of different materials,
which interalia requires a movement of the substrates into a number of vacuum
chambers without breaking the vacuum. Usually a belt conveyor is used to move
the carrier. The carrier weighs about 8-10 kg. A large size (~lm x 0.8 m)
carrier moves on stainless steel (ss) belts which are prefabricated with
dimensions using special type of welding. These belts pass through tensioners to
provide required tension to the ss belts so that the belt does not slip on the
rollers while carrying the load of carrier. The joint of the belt should be such that
the thickness of the belt does not change much which can shift the carrier
position and the process conditions may change. The process conditions do not
allow any variation in belt thickness by more than 0.5 to 1 mm. The thickness of
the belts is usually in the range of 0.1 to 0.3 mm. The movement of the belt is
also very slow for example, in the range of 10 to 50 cm per minute. If the belts

break these need to be replaced by new prefabricated belts of exact dimensions.
This requires either full of partial removal of the transport assembly which is a
cumbersome process and requires very fine re-alignment after replacing the
transport assembly back into the vacuum chamber. Any known technique of
repair by spot welding of the damaged belt is not technically acceptable as the
belt has to pass through a plurality of tensioners, and the belt normally bends at
radiuses of about 1-1.5 cm at two places. The sharp bends thus formed require
that the repair- joints be absolutely flexible, which call for specialized type of
welding, because any other type of spot welding of ordinary type makes the
repair - joint brittle and the belt breaks after a few runs. Maintaining a huge
inventory of spare belts of all sizes is expensive. In addition, replacement of a
defective prefabricated belt requires the entire transport assembly to be
dismantled fully or partially as it involves passing the belt on rollers which are
connected to motor or gear assemblies. Requirement of any small variation in
size makes the prefabricated belt useless.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to provide an improved process of in-
situ joining of damaged endless stainless steel belts or making new for
transporting wafer carrier into a vacuum deposition chamber, which eliminates
the disadvantages of prior art.

Another object of the invention is to propose an improved process of in-situ
joining of damaged endless stainless steel belts for transporting wafer carrier
into a vacuum deposition chamber, which eliminates the requirement of full or
partial removal of the entire transport assembly for the belt-repair.
A still another object of the invention is to propose an improved process of in-
situ joining of damaged endless stainless steel belts for transporting wafer carrier
into a vacuum deposition chamber, which substantially reduces frequent
replacement of damaged belt with a new transport belt of corresponding
dimension.
A further object of the invention is to propose an improved process of in-situ
joining of damaged endless stainless steel belts for transporting wafer carrier
into a vacuum deposition chamber, which reduces the operational cost including
cost of maintaining a huge inventory of different sizes of transport belts.
A still further object of the invention is to propose an improved process of in-situ
joining of damaged endless stainless steel belts for transporting wafer carrier
into a vacuum deposition chamber, which reduces the down-time and increase
productivity.

SUMMARY OF THE INVENTION
According to the invention, the belts are made by using running ss tape. The ss
tape is passed through all the rollers including tensioners and then marked
appropriately. The ss tape is removed from the transport assembly and is held
tightly in a vice. Using a flat file, slots of required width and depth are made.
Strips of copper are kept ready. The ss tape is then passed through all the rollers
of the transport assembly and is held tightly. The copper strips and are wound
around the tape in the slots. The copper strip is pressed hard using pliers or
hitting it softly using a light hammer. Using a soldering iron and common solder,
the copper strip joint is soldered. Now the belt can be used like any other welded
belt. Belts using this technique have been fabricated and damaged belts
repaired.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1(a) - shows the ends of a stainless steel (ss) belt with configured slots;
Figure 1(b) - shows copper strips cut from a copper sheet.

Figure 1(c) - shows the copper strips wound around the slots.
Figure 2(a) - shows the ss belt with copper strips folded and soldered.
Figure 2(b) - shows the endless ss belt with copper strips folded and soldered
ready for use.
Figure 2(c) - shows the endless ss belt disposed on rollers of the transport
assembly.
DETAILED DESCRIPTION OF THE INVENTION
As shown in figure 1(a), the ss tape is passed through all the rollers including
tensioners and then is held tightly by overlapping the tape and firmly holding it
using pliers. Using a permanent marker, to mark ss tape such that it overlaps
about 5 cm. The ss tape is removed from the transport assembly and is held in
between two wooden pieces in a vice in such a manner that only 1mm tape is
exposed out of wooden block, which allows constructing accurately sized slots.
Using a flat file, the exposed portion of the tape is filed making a slot equal to
the thickness of the file (about 2.5 mm) and 1mm deep. At least four slots are
made on each belt (Fig 1(a)). Strips of about 2.4 mm width are cut from a

copper sheet and kept ready (Fig 1(b). The ss tape is then passed through all the
rollers of the transport. The tensioner's tension is released and the belt is held
firmly using a vice grip plier so that the slots exactly overlap. The copper strips
are wound around the tape in the slots of 2.5 mm (Fig (c)). The copper strips
are pressed hard using the pliers or hitting it softly using a light hammer. The
length of the copper strips is kept such that it does not overlap. Using a
soldering iron and a common solder, the copper strip joints are soldered. This
adds more strength to the joint. The tension of the tensioners is restored and the
vice grip pliers is removed leaving the ss belt on the rollers. Now the belt is
ready to be used like any other welded belt. This technique can be used in any
transport of vacuum deposition system.
Using the technique, the damaged belt is also repaired by adding a small portion
of any other old belts. The dimensions shown in the figure have been arrived at
after a number of experiments using different slot sizes and belt overlap lengths.

WE CLAIM:
1. An improved process of in-situ joining of damaged endless stainless steel
belts or making new for transporting wafer carrier into a vacuum
deposition chamber, the transport belt encompassing at least one
powered roller and an idle roller located at space-apart positions on the
transport assembly and provided with at least two tensioners of different
diameter distantly positioned, the method comprising the steps of :
- passing a piece of stainless steel tape over the running rollers including
the tensioners and firmly holding the piece by a plier when overlapping
the ends of belt;
- marking the ss tape with a permanent marker such that it overlaps at
least about 5 cm;
- removing the marked piece from the transport assembly and holding
between two wooden pieces in a vice so that only 1 mm of the tap gets
exposed out of the vice;
- constructing at least four slots of 2.5mm width and 1 mm depth on the
exposed portion of the tape;

- preparing equivalent number of copper strips of about 2.4 mm width cut
from a copper sheet and wound around the tape in said slots; and
- soldering the copper strip joints, and allow the repaired belt to operate on
the transport system.

2. The method as claimed in claim 1, wherein the slots are made by a flat
file.
3. The method as claimed in claim 1, wherein the copper strips after being
wound over the ss tape is pressed by a light weight hammer.

ABSTRACT

The invention relates to an improved process of in-situ joining of damaged
endless stainless steel belts or making new for transporting wafer carrier into a
vacuum deposition chamber, the transport belt encompassing at least one
powered roller and an idle roller located at space-apart positions on the transport
assembly and provided with at least two tensioners of different diameter
distantly positioned, the method comprising the steps of passing a piece of
stainless steel tape over the running rollers including the tensioners and firmly
holding the piece by a plier when overlapping the tape; marking the ss tape with
a permanent marker such that it overlaps at least about 5 cm; removing the
marked piece from the transport assembly and holding between two wooden
pieces in a vice so that only 1 mm of the tap gets exposed out of the vice;
constructing at least four slots of 2.5mm width and 1 mm depth on the exposed
portion of the tape; preparing equivalent number of copper strips of about 2.4
mm width cut from a copper sheet and wound around the tape in said slots; and
soldering the copper strip joints, and allow the repaired belt to operate on the
transport system.