Note: Descriptions are shown in the official language in which they were submitted.
CA 02617502 2008-01-31
DESCRIPTION
DEVICE FOR RECEIVING OR HOLDING SEVERAL
SUBSTRATES AND GALVANIZING DEVICE
FIELD OF APPLICATION AND PRIOR ART
The invention relates to a device for receiving or holciing several flat
substrates in one plane, as well as a galvanizing or electroplating device
with
a passage path for the substrates through a treatment chamber, the sub-
strates being held in an aforementioned device.
Hitherto substrates have been conveyed on conveyirig rollers lying in
the manner of a roller conveyor in galvanizing devices for substrates, such as
e.g. printed circuit boards or more especially solar cells or wafers. However,
this can give rise to problems in the case of very sensitive substrates, such
as
e.g. thin solar cells. Here the substrates can be formed from very thin
silicon,
which is correspondingly sensitive or fragile. In addition, sensitive
substrates
have to be handled with extreme care, e.g. on introduction into a galvanizing
device. In many cases this means either increased mechanical expenditure
for the gripping devices or a decelerated handling, which giives rise to unde-
sired delays.
PROBLEM AND '>OLUTION
The problem of the invention is to provide an aforementioned device for
receiving or holding several flat substrates, as well as a galvanizing device
suitable for the working thereof, enabling the problems of the prior art to be
avoided and permitting a more careful working and conveying of the sub-
strates.
This problem is solved by a device having the features of claim 1 and a
galvanizing device having the features of claim 13. Advantageous and pre-
ferred developmertts of the invention form the subject matter of the further
CA 02617502 2008-01-31
claims and are explained in greater detail hereinafter. By express reference
the wording of the claims is made into part of the content of the description.
According to the invention the device has a frame with frame pieces
forming reception zones between them and as a result of the frame pieces
recesses or cutouts are formed. The frame pieces can e.g. run in grid-like
manner, particularly with an outer frame and intermediate frame pieces as
subdivisions. The frame pieces have supports for the substrates on which
the substrates rest. Thus, the mechanical ho9ding of the substrates and/or an
electrical contacting takes place on the substrate side engaging on the sup-
ports. In this way a reception device or holder for several flat substrates
can
be created, in which the substrates are placed in the reception zones. For
various treatment steps with respect to the substrates, as well as for convey-
ing and in certain circumstances also storage, there is no rieed to move the
ind'ovidual substrates and instead the complete reception device is moved.
The latter can be made more robust than the substrates, so that it is readily
possible to use conventional gripping devices or the like. As a result of the
supports there can be a precisely defined connection between the reception
device and the substrate, which can be matched to specific substrate charac-
teristics. As a result of the reception device it is possible iri the case of
a plu-
rality of substrates to not only move one substrate in connection with individ-
ual working steps, but instead all the substrates of a reception device can be
moved. If electrical contacting with the substrates takes place via the recep-
tion device or the supports, in certain cases it is possible to economize addi-
tional contacting devices directly on the substrates. This also has the advan-
tage that the mechanical loading of the substrates by contact rollers or other
contacting devices can be reduced or avoided. Thus, advantageously the
reception device brings about both a mechanical holding or reception of the
substrates and also an electrical contacting thereon.
-
The supports can e.g. be constructed as projections, which project or
emanate from the frame pieces. The projections can either be relatively nar-
row, i.e. almost punctiform, in order to bring about a very limited surface
cov-
erage on the substrates. This permits a contact with a treaitment medium in a
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CA 02617502 2008-01-31
galvanizing device in an advantageous, very large-area manner. Alternatively
the projections can be wider in order to bring about a type of linear
supporting
of the substrates with their marginal area on the receptacles or frame pieces.
This permits an adequately stable supporting or bearing action, especially
with sensitive substrates, because.there is a distribution thereof. The projec-
tions can also run below the plane of the frame pieces, e.g. by a downward
bend. This makes it possible to have the bearing substrates in roughly one
plane with the holder or the frame pieces. It is also possible for the projec-
tions to project downwards over the plane formed by the uriderside of the
frame pieces. Advantageously the substrates rest in the reception device or
on the projections in such a way that their top side is not below the plane of
the top side of the frame pieces and instead preferably projiects by a small
amount. This makes it possible to ensure that rollers or the like engaging
from above in all cases also engage on the top side of the substrates and not
mainly on the frame pieces projecting over the substrates.
For etectrical contacting purposes it is possible to provide on the sup-
ports special contacts which project upwards. Through said contacts, which
are in particular fitted separately to the projections, electrical contacting
can
be improved independently of the material or construction of the projections.
Contacts can be iri the form of contact projections, contact points or contact
studs with electrically conductive surfaces. In particular, the contacts can
be
made from contact material advantageously used for switching contacts. In a
development of the invention it is possible to provide them with seals in such
a way that no electrical contact takes place when the substrates are applied.
Thus, in the case of a galvanizing process undesired deposits on the contacts
can be avoided, because the treatment medium cannot corne into direct en-
gagement with the contacts as a result of the seal. It is e.g. possible to
have
cup or pot-shaped rubber seals around the contacts.
39
It is advantageous for electrical contacting if some or all the frame
pieces are electrically conductive. In particular the entire rE:ception device
is
electrically conductive and can e.g. be made from metal. Advantageously all
parts or frame pieces of the reception device are electrically conductively in-
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terconnected. For this purpose such a receptacle can be rough worked from
a metal sheet in the manner of a grid-like tray.
[In a further development of the invention, it is possible to provide the
reception device with an electrically insulating coating, e.g. paint or a
cover-
ing. This avoids any deposition of coating material on the ireceptacle during
a
galvanizing process. If such deposition of coating material e.g. takes place
on the aforementioned contacts as exposed surfaces of the reception device,
then at certain time intervals said contacts must be cleaned or stripped free,
as is known to the expert.
A part or section of the device can project on an outside, particularly an
outer area or from an outside frame piece. This is advantaigeously bent up-
wards from the plane of the substantially flat device, particiularly with a
further
sideways bending following onto the same. If said projecting section is e.g.
electrically conductively connected to the frame pieces or electrical contacts
for the engagement of the substrates, then via said sectiori there can be an
electrical contacting with the reception device. For this purpose, e.g. the
sec-
tion can be made from the same material as the remaindei- of the device, e.g.
it can be rough worked from the aforementioned metal sheet. It is advanta-
geously possible to construct the entire reception device integrally or in one
piece. Said section can also be used for the gripping of the reception device
in an area which is remote from the inserted substrates, sci as to provide pro-
tection for the sanne.
In a further development of the invention it is possible to construct the
reception device in such a way that a substrate is sealingly located in a re-
ception zone between adjacent frame pieces. Thus, all the reception zones
of a reception device carry substrates and in this way form a substantially
liq-
uid-tight surface. The sealing or tightness requirements must at least be such
that in the case of movement through the treatment mediuim or a liquid bath
liquid does not penetrate from below through the areas between the substrate
and the frame pieces, this applying in the case where the pressure of the liq-
uid from below is only limited. For this purpose it is e.g. pcissible to have
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seals along the frame pieces or along the areas where the substrate sides
are close to the frame pieces. This makes it'possible to keep the top side of
the substrates and also the reception device free from treatment liquid. This
is especially advantageous if there is to be a treatment or coating only on
the
downwardly directed side of the substrates.
Advantageously the reception device is constructed for identical sub-
strates and each substrate is then held in the same way. To this end several
reception zones are provided successively in juxtaposed manner, e.g. with an
overall rectangular zone. -
[In a further development of the invention onto the reception device can
be fixed a covering device or cover, particularly in a movable or articulated
manner. Substrates placed in the reception device can be fixed by the cover
or secured against dropping out or becoming detached. The cover can cover
roughly the same surface area as the reception device. Acivantageously it
has a similar structure with pieces and interposed zones. Particularly advan-
tageously it is constructed in a substantially similar or almost identical
manner
to the reception device. If the substrates are also held or secured from above
in the reception device, easier movement thereof is possiblle and in
particular
can be held vertically or even rotated. If the cover is fixed at a number of
points to the reception device, it can be made much thinner or weaker, be-
cause it does not necessarily have to form an independent'ly supporting struc-
ture. Its function is solely to hold the substrates in the reception zones of
the
reception device.
For the inventive galvanizing device it can be provided that the sub-
strates run through the treatment chamber. The latter contains a treatment
medium, e.g. an electrolyte, for the galvanic application of a coating to the
substrates. The substrates can advantageously be thin printed_circuit boards
or alternatively thin solar cells, as described hereinbefore. The passage path
has conveying means, e.g. conveying rollers, wheels, etc. By means of the
latter the above-described reception device is conveyed or runs on the pas-
sage path through the treatment chamber. On the reception devices or on
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the substrates can engage pressure rollers, wheels or the Ilike for various
dif-
ferent functions. Ilt is possible for there to be at least one such pressure
roller
in the passage dir=ection for each successive row of substrates. If the sub-
strates are very sensitive, as stated hereinbefore, the pressure rollers are
ad-
vantageously pari:icularly soft so as not to damage the substrates.
An aforementioned reception device projects laterally over or away
from the substrate plane and is in particular bent upwards. The angular sec-
tion extends to an aforementioned electric contacting mearis and is advanta-
geously not in coritact with the treatment medium or is positioned outside the
galvanizing device. It is particularly advantageous to bend the reception de-
vice upwards and then to the side, so that the end projects over the galvaniz-
ing device. Electrical contacting can take place through erigaging contacting
rollers or jointly running contact clips or other contacts, such as also
contact
brushes.
Advantageously the treatment medium extends to the underside of the
substrates passing through or up to the latter. In order to keep the top of
the
substrates dry and clean, it is possible for the height level to extend
relatively
precisely to the uriderside of the substrates. This can lead to a type of wave
formation in the treatment medium, in order that the underside of the sub-
strates is reached by the weak waves or with their wave crests. Alternatively
substrates can be sealingly placed in the reception device, as described here-
inbefore.
Electrodes or the like for the galvanizing process cari be provided be-
low the substrates. If the substrates pass in fully immersed manner through
the treatment medium, electrodes can also be provided above the same.
In another embodiment-of the invention on the top side of the reception
device, e.g. between the pressure rollers, several contactirig means can be
provided forming an electrical contact with the substrates. They can be con-
structed as circumferential contacting rollers. For this purpose they can e.g.
engage on the frame pieces, advantageously running in the conveying direc-
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tion. It is particulEirly advantageous to provide at least one contacting
means
on each frame piece running in the conveying direction.
These-fr-ame pieces, on which the contacting means engage, can be
advantageously higher than the substrates in the reception device. Thus,
they are generally above the liquid bath level. They are also electrically con-
ductive. For contacting the substrates, besides an aforementioned, com-
pletely conductive frame, contact bridges can be provided, which run from the
frame pieces with the contacting means to the substrates located therein.
They can have a bow or bridge-like construction and lead bilaterally from the
frame pieces to the substrates and e.g. the substrates can rest on ends of the
contact bridges. This permits electrical contacting of the substrates even
without conductive frames.
Between in each case one pair of pressure rollers can be provided a
contacting roller, preferably on the same shaft. The contacting means, pref-
erably contacting rollers, can be constructed resiliently or elastically,
particu-
larly with contactirig surfaces projecting resiliently from a solid central
part.
They can be segniented, but this generally only serves to provide a more re-
silient construction.
These and further features can be gathered from the claims,, description
and drawings and the individual features, both singly or in the form of sub-
combinations, cara be implemented in an embodiment of the invention and in
other fields and can represent advantageous, independently protectable con-
structions for which protection is claimed here. The subdivision of the appli-
cation into individual sections and the subheadings in no way restrict the
general validity of the statements made thereunder.
- BRIEF DESCRIPTION OF THE DRAWINGS
An embodiment of the invention is described in greater detail hereinaf-
ter relative to the attached diagrammatic drawings, whereiri show:
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Fig. 1 A sloping view of an inventive reception devic;e.
Figs. 2 & 3 Larger scale detail views of the reception device of fig. 1.
Fig. 4 A sectional representation through an inventive galvanizing de-
vice for solar cells.
Fig. 5 A side view of the galvanizing device of fig. 4.
Fig. 6 A sloping view of another inventive galvanizirig device.
Fig. 7 A larger scale detail view of the contacting oni the reception de-
vice of fig. 6.
DETAILED DESCRIPTION OF THE EMBODIMENT
Fig. 1 shows in a sloping or oblique view a reception device 11, which
is constructed in the manner of a tray. Outside external frame pieces 12 and
intermediate inside frame pieces 14 form a type of grid or lattice with re-
cesses between them, so as to constitute reception zones 20. It can be seen
that all the reception zones 20 between frame pieces 12 and 14 are of the
same size, although this need not be the case.
On the rightwards-directed side is provided an angular section 16.
Here the outside frame piece 12 is firstly bent upwards anci then with a mar-
ginal strip 17 to the side again. The reception device 11 can be made from
metal, particularly a sheet metal plate. It can be coated in insulating manner
with a covering or a paint, which is resistant to the treatment media
generally
used during galvanizing. The marginal strip 17 is free on at least one side or
has an electrically conductive surface, advantageously this is on both sides.
Particularly the larger scale view of figs. 2 and 3 reveals how at a num-
ber of points projections 22 project from the frame pieces 12 and 14. They
can either be fixed subsequently to the frame pieces, e.g. by welding, or al-
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ternatively they can be rough worked by a punching process or the like from a
single metal sheet together with said frame pieces. The sectional view of fig.
3 shows that the thickness of the projections 22 is less=than the thickness of
the frame pieces and in particular they are only half as thick. As a result in
the
case of the solar cells or silicon wafers 26 resting on contacts 24 located at
the end of projections 22, as shown in broken line form in fig. 2, the top
side
of the solar cells is not too far above the top side of the reception device
11 or
frame pieces 12 aind 14. This is explained in greater detaill hereinafter rela-
tive to figs. 4 and 5.
The contacts 24 can e.g. be contact points or tips and can be made
from a contact material normally used for switching contacts or the like, i.e.
from a different material to the projections 22. This has the advantage of
even better contacting with the solar cells 26 or other substrates to be
placed
in the reception zones 20.
In alternative developments of the invention, in place of the individual,
relatively small projections 22, wide strips project from the frame pieces 12
and 14 permitting a wider engagement of the solar cells and consequently a
better mechanical support. It is also possible to have more than the three
projections 22 shown for each reception zone 20 and they are in particular
distributed over all the frame pieces. The advantage of a small number of
projections 22 is the ease of manufacture. In addition, as a result the treat-
ment medium is applied particularly well to the underside of the substrates or
solar cells.
In a further development of the invention it is conceivable to have circu-
lar seals or the like around the contacts 24 at projections 22 in such a way
that the contacts 24 engage on the solar cells 26 in a substantially
punctiform
area. This engagement area is surrounded by the seal and shielded to the
outside, the seal being as close as possible to the contacts in order to keep
the engagement area as small as possible. In this case the contacts are pro-
tected from coming into contact with the treatment medium and are in this
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way not coated. The precise construction of such seals is known to the ex-
pert and can be innplemented without difficulty.
in the representation of a galvanizing device 30 in fig. 4, walls 31 form a
treatment chamber 32 housing an electrolyte as a treatmerit medium in which
is dissolved the metal which is to be deposited on the solar cells 26. The re-
ception devices 11 according to fig. 1 are conveyed lying on, conveying
rollers
33 through the galvanizing device 30. The conveying rollers 33 are driven by
a drive 34. As cael be seen in fig. 5 and as is generally known, numerous
conveying rollers 33 are successively arranged and form a passage path for
the reception devices 11 or solar cells 26.
At each reception zone 20 the reception device 11 is covered by a solar
cell 26. The pressure rollers 36 engage on the top side of solar cells 26 in
galvanizing device 30. They comprise a very flexible rubbE;r covering 37 on a
metal core 38 andl are also driven by drive 34. The pressure rollers 36 are
positioned in such a way that they in each case rest relatively precisely cen-
trally along the rows of successive solar cells 26. The function of the pres-
sure rollers 36 is to hold the solar cells 26 in the reception device 11 or
recep-
tion zones 20 and to ensure the engagement of the contacts 24 on the under-
side.
The angular section 26 of reception device 11. projects upwards at least
over the level of the treatment medium in the treatment chamber 32. The
rightwards-projecting marginal strip 17 projects over the right-hand wall 31
and beyond. A cc>ntact roller 42 contacts the underside. Iri much the same
way as for the conveying rollers 33 and pressure rollers 36 in fig. 5 a
plurality
of contact rollers 42 is provided along the passage path. B,y means thereof
there is a constant electrical contact with the marginal strip 17 and conse-
quently the reception device 11. -The contact roller 42 is orice again con-
nected to a power source 44 or its negative pole. The positive pole of the
power source 44 is connected to elongated electrodes 40, which are posi-
tioned between the rollers above and below solar cells 26 in treatment cham-
ber 32.
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FUNCTION
The-solar cells 26 are placed in the reception device 11 for treatment
purposes. Electrical contacting of the solar cells with the reception device
11
takes place via the contacts 25 engaging with the underside. By means of a
not shown covering device or the like the solar cells 26 cari be firmly held
in
the reception zones 20, e.g. by a further, grid-like frame, ciiips, etc. In a
fur-
ther development of the invention springs or the like can be provided which
press the solar cells 26 into the reception zones 20 or agaiinst the contacts
24
and are automatically locked on inserting the substrates. Finally, it would
also be possible to have small suction cups, a vacuum holding means, etc.,
e.g. in the vicinity of projections 22, They can also embrace the contacts 24
with the aforementioned sealing function.
The solar cells 26 are advantageously made from silicon or are silicon
wafers. Hitherto they have been printed on in complicated manner in part
with silver paste as the contact material. The galvanizing clevice 30 is pro-
vided to galvanically deposit the contact layer, particularly on the front of
the
solar cells. Thus, the treatment medium in the treatment chamber 32 con-
tains a corresponding proportion of contact material, e.g. siiiver.
The reception device 11 containing the solar cells 26 is then introduced
into the galvanizing device 30. The reception device 11 moves along the
passage path on conveying rollers 33 through said treatment chamber 32. If
deposition of silver is only to take place on the underside of the solar cells
26,
the height of the treatment medium can be correspondingly chosen or the
treatment medium should only extend to the underside of the solar cells 26.
- The solar cells 26 are electrically conductively connected by their un-
derside via contacts 24 and projections 22, as well as frame pieces 12 and 14
with the angular section 16 or marginal strip 17. As contact rollers 42 extend
up to the marginall strip 17 and are once again connected to the negative pole
of power source 44, the undersides of the solar cells 26 are at this
potential.
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By means of electrodes 40 connected to the positive pole of power source 44,
voltage is applied or the potential gradient to the solar cells 26 is built up
for
the deposition of silver from the treatment medium on the underside of solar
cells 26. Process p-ararrmeters,_such as_the passage speed and composition
of the treatment medium and the operation of the power source 44, are in
each case to be chosen as a function of the given application and provide no
problem to the expert. Following adequate silver deposition or coating, the
reception device 11 with solar cells 26 is removed or extended out of the gal-
vanizing device 30. This can be followed by a further treatrnent or an inter-
mediate storage. For as long as the solar cells 26 are not individually re-
quired or worked, they can be left in the reception device 11. In the latter
they can be easily conveyed, stored and protected against damage.
As coating nnaterial is also deposited on the receptiori devices 11, at
least on contacts 24 if they are unprotected, the coating is to be removed
therefrom at certain time intervals. This process is called "destripping'a by
the
experts. It is advantageous if the reception device 11 only has an
electrically
conductive surface in the vicinity of contacts 24 and marginal strip 17, be-
cause then no coating can take place in the remaining areas. Alternatively to
the aforementioned removal of a coating, this can take place in a wet chemi-
cal manner.
Fig. 4 shows how the pressure rollers 36 in each case press the solar
cells 26 into the reception zones 20. As the top of the solaf- cells 26
project
slightly over the top of the frame pieces 12, 14, it is ensured that the
pressure
rollers 36 always engage on the substrates or solar cells 26 and consequently
press the latter downwards against the contacts 24.
In addition to the power source 44, there can also be light sources be-
low the solar cells 26. They can assist the coating process by irradiating the
solar cells 26 from below with light of a suitable wavelength, preferably in a
range 400 to 1100 nm. In certain circumstances it is even conceivable for the
necessary galvanizing current to be produced solely by the light sources.
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However, advantaigeously such a light-induced current generation is com-
bined with an aforementioned, controlled power source.
In the alternative variant according to figs. 6 and 7, a frame-like recep-
tion device 111 with outside frame pieces 112 and inside frame pieces 114 is
covered with substrates 126. They are conveyed by conveying rollers 133
through a plant similar to that described hereinbefore. Substrates 126 are
held by pressure rollers 136 in the reception device 111. The pressure rollers
136 are located on the same shafts 150 as the intermediately provided con-
tacting rollers 152. The latter have resilient contact zones 154 projecting
from
a central part 151 The contacting rollers 152 or contact zones 154 engage
on the top of the frame pieces 114. The latter are continuously electrically
conductive or have a corresponding coating or support.
From said electrically conductive frame pieces 114 contact bridges 155
project bilaterally. They can alternatively be in the form of clips or have
some
similarly functionirig shape. The contact bridges 155 pass into ends 156 on
which rest the substrates 126 and are in this way electrically contacted in
the
aforementioned manner with the contacts 24.
It is advantageous here that an electrical contacting on the frame takes
place in surface-distributed, central manner, i.e. not only from one side.
Thus, there are no current gradients. In the case of local contamination on
one contact surface, there is much less risk of an interruption of the power
supply. The indiviidual current supply to all the fram&pieces 114 in the pas-
sage direction is cslso conceivable, if further measures of galvanic
separation
or isolation from electrolysis are carried out.
13
