Note: Descriptions are shown in the official language in which they were submitted.
'~ z~ 4~ ~0~
FROM : TEL: JRN.25. 1995 10:08 HM P14
WU 94/03G5r~ 1'CT/L7h,93/OOG84
I'C:1'/L)1/c)3
A'1'()'I'1?C:IwI f)I~:UTSC;HI.AN1) GMI;Id, Berlin f)t
I'50~20 1'C:'1'
Lt:v.i:...,l~vlyti~c~ro~css~,tg of.J.'.ul>'~-~uir.
fans...~atit.lt..rD_rillings.~tud
~L1~',l'~11~11L.~LI1.~2~111't;J1t111~,.4hC! 1~1'VCPSS
'I'hc invcnticm relates, first, to a process far the clrca.rolytic proccs,ing
of printed circuit boards
wirh drillings, which arc. taken through a treatment bath or to a prac:essing
action by
cnnveyor means, in which there are ntcans for reducing the thickness of a
metal-ion-depleted
region (diffusion cone), which arc in contact with the printed circuit hoards.
'1'Ire preferred
area of use fur the invention i;; galvanization, w)tich will be discussed in
store detail below.
The invention can also he used in clecarolytic etching.
The surface of the items to be processed or their diffusion layer bcc~mcs
deplet.cd of metal
ions in a disadvantageous manner
~1~~60~~
FROM : TEl_: .TRN.25.1995 10:09 f~'1 P15
WC) 9~1/0:~~55 I'C:'1'/1.)L;93/OOG84
during prcu~~ssing, hacauso the c~athc~dc~ draws ntc~re inns to it then
usually come: out c~f the
surrounding wcatrrt~nt Lath. ''('his leads to a rc~durtion in tltc accrptahle
apcoific. current:
dc:vsit:y, .tncl thus means that in order to achieve such a metal coaring
havity a particular
thiclcncss, a rorrcspondingly long treatment time is needed.
In order to omrcomc this disadvantage, t:hc so-called "high-sl.~ecd" process
can be used, in
which the clcct:rolytc is ronduetcd ac great speed and in great: quantity
along the catholic
surface be.t:wecrr this surfacx and the~, anode (scr; Curopean 1'atcnt 0 14z
010 and German Patent
35 25 183, lcrr example). It is true that using this prUc~ess, an improved,
i.e. increased, e:urrettt
density of the. mcaal coating an t)tc cat.h~dic it:csrn is achieved. Idowev~r,
the production,
cant.rc~1 and discharge c~f such an electrolytic current is relatively
expensive, The creation of
the flow channels necessary for this requires acldcd con~truccivc
expenditures. In addition, the
nranncr of ccmvc:ying tha items to be processed cart be complicat:cd. 1=~c~r
these reasons, it has
bcrottte known only for continuous items iv be hroc:essed, such as strips or
wires.
!n the article "L:Iectrolyuc IIiKIt-Power C)vc~rgalvttniiation of Steel Strip
through Boundary
layer Control" ("I~Ic~c.trvlyt~.cclxr hloc-lihistun~;rlvt>>zi.r~krtng qxm
,S~a.hllx~nd drc~~v tttech~>t.ascvre
Grcrmcchicl.~t.lxc:~n~lrssautt~,") by T~. Meuthen ttnd f). Wolfhard in the
journal ~, I S t
(Mcnrrloh~rf)ric'htr .3<) (1982, pp. 70-75), a process for t.hc electrolytic
galvanization of steel strip
is described, in which the strip surfacr. to be galvaniLed is pressed against
and moved relative
t:v :t notrvvovcn fabric, similarly to in the so-callc~.d tampon or hruslt
galvanizinfi proccas. 'rite
2
~I~~.vO~
FRl7M : TEL: Jf~~1.25. 1995 10:09 HM P16
VL'O ')4/03655 PC'1'/h1:c)3/00684
coatinb 4lrcarc~lyte is rinsccl thrciugh the n~tnwcwrtt fabric onto the steel
surface. 1-ligh4r
current density is achieved tltrcnrgh thix procc~.ss during electrolytic
r.inc: deposition,
A similar principle is also, a;t.scribcd in 1?urapcan !'atent Aprlicatioti 0
210 072 for the
electrolytic: casting crf small mc~ta) parts which arc coated with rtol.~lc
metals, hspcrially for use
as plug-type contt~ctors.
J~urlhc~.rmc~re, a prcrcc.ss for the coating ctf surfaces is known from 17.5,
Pat. No. 3,706,650, in
which nem-conductive, fluid-storing, porous, compressible m4ans arc pressed
against the
surfaces to be coated and rnoved relative thereto, whereby the saunter-
electrode to the object
to W . Cnatc.d is located in the interior of these rncans. The. elect.r~lytic
fluid flows from the
outsidr. to t.hc contact surfaces between the Porous, c:ompressihlc means and
the surfaces t.o be
coated. '1'lrc porotm, cc~mhressi~~lr, means also contains hard non-
conductivt: particles, which
somewhat roul;hen the surfaces of the metal work piece to be coated.
In the three aforementioned documents, no refercnc:e is made tc~ the flaw
through drill hales
required irr the manufacture of printed circuit boards, because ir1 all cases
the surfaces to be
ce»ted arc either flat or mrrG.ly curved.
In the German Document fcrr Pubic Inspection 14 4G 045, a procass far
galvanization with
sirrruhaneous clcctrolYtic cleaning of metal. surfaces and
za
~1.!~~.b~l~
FROM : TEL: JRN.25.1995 10:10 RM P17
WC:~ c)4/03G55 1'C:'!'/1_)L,y3/OOG84
a clevic~ fur implcmeittinG this hr~~c~ss arc~. discle~scd. What is involved
in this case is the
coating of large drillings in atecl with the help of an inner electrode, tha
nuter areas c~f which
art: rrrUhcd on the inner areas of tlu~ drillings, A device of this type is
not: suitable:, however,
for the electrolytic prcwessity c~f printing circuit. I~aardc with drillings,
I~rum 1.)F:-OS 3G 03 8r>6, a hr~coss and ;t device for galvanising flat items
such as priotrd circ:ui~
ho.trds arc known. 'I'hc flat items :trc grasped and transported by a
cathodically connected
roller pair rc~cating at a rel;wivc~ly slow ratzti~oal shoed, '1'hc
electrolyte is ~PPlied to the item
by ;tn anodically conoecaed roller pair, the surflcc of which can absorb
fluid, A sm;tll
2b
'.-
WO 94/03655 PCT/DE93/00684
distance is deliberately maintained between the surface of the item and the
surface of the
anodic rollers. The rotational speed of the anodic rollers is relatively high,
in order to attain
a correspondingly fast electrolytic movement along the surface of the item. In
this way, an
increase in current density is achieved, compared to conventional immersion
bath
galvanization. Thus rotating, insoluble roller pairs as anodes are described.
The metal is
supplied in soluble fashion via the electrolyte. The anodic roller pairs are
not located below
the level of the bath; therefore the electrolyte must continuously be applied
to the
galvanization location. The quantity of supplied electrolyte is limited, not
least of all due to
the close plastic screenings over the rollers. This also limits the possible
galvanization current
density. The plastic screenings are needed, however, in order to delay an
undesired
galvanization of the other, cathodically-connected roller pairs, which serve
to transport the
circuit boards.
Because the rotating anodic roller pairs do not touch the upper sides of the
circuit boards, the
diffusion layer located on the surface is not mechanically disturbed. However,
the space
between the anodic roller and the upper side of the circuit boards and thus
the space between
the pairs themselves is needed, to allow the galvanizing currents for the two
sides of the circuit
boards to be individually set. During galvanization of the conductor path
image, this is always
necessary, because the two sides of the circuit board, in practice, have
uneven copper areas.
For this reason, the anodes of the upper side of the circuit board are fed
from one bath
current rectifier and the anodes of the bottom side are fed from a
3
VUO 94/03655 ~ ~ ~ ~ ~ ~ ~ PCT/DE93/00684
different rectifier. Each rectifier can be individually set in respect to
current.
Another disadvantage of the aforementioned invention is the very poor flow
through fine
holes in the printed circuit boards. On board sides located opposite to one
another,
electrolyte is applied in a small quantity in an almost pressure-free manner.
This prevents the
flow from going through the holes, resulting in inadequate galvanization of
the hole walls even
to the point of burns in the holes.
The invention is based on the problem of designing a generic process so as to
achieve the
desired reduction in thickness of the ion-depleted border layer on the anode
surface or cathode
surface (diffusion layer), and to thus attain a correspondingly increased
current density of the
galvanization current flowing from the electrolyte onto the anodic or cathodic
item, while
avoiding, however, the constructive and process-related expenses of the so-
called "high-speed"
flow technique.
This problem is solved and this object attained, first, starting from the
generic prior art, in
that in the presence of an anode and cathodic items to be processed, or in the
presence of
anodic items to be processed and a cathode, the surface to be treated of the
items is wiped
continuously by machine and the electrolyte is conveyed by a component
vertical to the plane
of the items and is passed through the drillings or drill holes (referred to
hereinafter for the
sake of simplicity as "drill holes") of the items.
4
CVO 94/03655 ~ 1 L~ ~ ~ ~ ~- PCT/DE93/00684
This wiping of the area or areas in question serves, in a simple, advantageous
and industrially
implementable manner, to counteract the disadvantageous depletion of metal
ions in the
diffusion layer. The diffusion layer is largely destroyed, and thus the ion-
depleted zone on the
surface or surfaces in question is completely or at least largely eliminated.
The metal ions of
the electrolyte can therefore make their way directly onto the surface of the
items in question,
or, during etching, can be removed therefrom. In respect to further
advantages, reference is
made to the discussions below of the various possible designs of the
invention, in respect to
both process and object. By means of the combination according to the
invention of the
aforementioned wiping and the metallization of the surface which this achieves
with the
metallization of the inner walls of the drill holes based on conveying the
electrolyte through
the drill holes, an adequate treatment of the inner wall of the drill holes is
simultaneously
achieved, and thus the metallization of the treatment items is achieved on all
required areas
(surfaces and drill holes) with satisfactory results in one work step and
using relatively simple
measures. In this connection, the aforementioned combination has the advantage
that the
wiping sequence destroys any surface tension existing on the fluid in the
drill holes, making
it even easier to metallize the drill hole inner wall. As the examples of this
invention show,
the structural means for wiping, on the one hand, and for conducting the
electrolyte through
the drill holes (so-called "flooding"), on the other,
..-
WO 94/03655 PCT/DE93/00684
can be provided together in a simple and space-saving manner, and in the
preferred design of
' the invention are even combined. Here reference is made, for example, to the
design according
to Fig. 15. A further advantage is that with the aforementioned flooding--
particularly when
this is still done by supporting a pressing of the electrolyte, e.g., by means
of a pump, into
the drill holes and/or a drawing of the electrolyte out of the drill holes by
means of a suction
device-any particles that might still be present in the drill holes can be
extracted from the drill
holes and transported away. This avoids the danger of particles trapped in the
drill holes
becoming embedded through metallization and of the drill hole in question
becoming clogged,
which leads to rejection of that particular circuit board.
Furthermore, in this connection, the danger is avoided of abrasive or chip
particles still
adhering to the edge of the drill holes being grasped by the wiping coatings
and transported
along the surface of the items to be processed, which can damage and even
render unusable
the delicate surface of the items to be processed.
A complementary attainment of the object is represented by a process in which
an appropriate
relative movement between the cathodic or anodic items to be processed on the
one hand and
an anode-side or cathode-side wiping device on the other hand achieves the
effect according
to the invention.
In achieving this relative movement, the transport movement of the items to be
processed may
be used
6
WO 94/03655 2 ~ ~ ~ ~ ~ ~ PCT/DE93/00684
.i
.3
:.~
as an alternative when the items are taken by conveyor means through a
treatment bath.
The further subclaims present preferred designs of the invention:
The possible process measures provided according to the invention for the
attainment of the
object may preferably be used for galvanization, but may also be used for
electrolytic etching.
The items (work pieces) to be processed thereby has an anodic function, i.e.,
it is anodically
connected. The etched-away metal is precipitated on a counter-electrode
(cathode). The
counter-electrode can be the wiping device. Then, in a later work step, the
precipitated metal
is carried away and re-obtained. Electrolytic etching of this type is an
alternative to purely
chemical etching. During electrolytic etching, a simultaneous wiping of the
anodes disrupts
a border layer appearing there.
In order to simplify the presentation of the invention, the invention will be
discussed below,
and in the description of the examples related to the drawings, in reference
to processes and
devices for galvanization.
The movement of the coated anode relative to the item to be galvanized,
whereby the coating
bears against the item, largely destroys the diffusion layer (see above) and
thus completely or
largely eliminates the metal-ion-depleted region on the surface of the items
to be processed.
7
~~c70 94103655 ~' ~ ~ ~ ~ ~ ~ I'CT/DE93/00684
The ions of the electrolyte can make their way directly through the coating of
the anode to
the surface of the item to be processed and metallize it. 1n this way,
relatively high current
densities can be achieved, and with good quality, particularly with an even
strength of metal
layer precipitated on the item surface, e.g., a copper layer. This is a
significant advantage,
which is especially important when it is not the entire area that is to be
coated, but only the
surface of conductor paths located on a circuit board of this type. A further
significant
advantage of the invention is that the distance between the anode and the
cathodic item is still
determined only by the thickness of the coating on the wiping device, whereby
this thickness,
however, can be relatively small. Due to the very small distance thus achieved
between the
anode and the cathode, different field line concentrations of the
galvanization current flowing
from the anode to the cathode practically do not exist, or at least exist to a
considerably lesser
extent than in arrangements in which a comparatively large distance exists
between the anode
and the cathode. In previously known arrangements with a relatively large
distance between
the anode and cathode, it was necessary, in order to avoid damaging effects
such as increased
metal precipitations on edge regions, e.g., the so-called "dog-bone" effect,
to make appropriate
expenditures, e.g., to provide "blendings." This is especially true in the
case of flat items to
be processed, such as electronic printed circuit boards, which have a great
many drillings.
Here, considerable scatterings (known as drill hole scatterings) can result on
the edge region
of the boards and in the drill holes.
8
r--
WO 94/03655 ~ ~ ~ ~ ~ ~ ~ PCT/DE93/00684
A significant advantage of the invention is that it achieves higher current
density values,
without the depletion of metal ions causing so-called "burns" or the like of
the metal to be
deposited. Blendings or similar measures against excessive scatterings of the
galvanizing current
are not needed. A further significant advantage of the invention is that it is
suitable for the
automatic galvanization of items running continuously through a unit
(perforated boards or
the like). This will preferably occur in the case of items arranged and
transported horizontally
(see, for example; DE-OS 36 24 481, discussed below). However, the invention
can be used
not only with horizontal, but also with vertical or slanted runs, and such
usage will be
accompanied by the advantages discussed above, particularly the avoidance of
damaging
scatterings at high current densities. When it is possible for higher current
densities to be
applied, as they can be as a result of this invention, the transport speed
also becomes faster or
the treatment route shorter. In particular, it is not necessary to ensure a
disturbingly high
flow rate of the electrolyte.
With the invention, a wiping effect is automatically achieved on the entire
surface to be
treated, in particular, on both sides or surfaces of flat items. For the sake
of completeness, it
should be mentioned that in manual galvanization, the process referred to as
tampon
galvanizing is known, used particularly for the processing, repair or
improvement of larger
components which cannot
9
~~ 1~~'~
WO 94/03655 PCT/DE93/00684
be processed or can be processed only with great difficulty in a galvanizing
unit. Typical
examples of this are the improvement or galvanization of metal church roofs,
large monuments
and the like. For details, reference is made to the publications of RUBINSTEIN
in the journal
Galvanotechnik ("Galvano-Technology") No. 73 (1982), pp. 120 ff; No. 79 (1988)
pp. 2876 ff
and pp. 3263 ff. Such a tampon process, however, can be used only for the
aforementioned
special cases, not for the industrial production of printed circuit boards
with drillings and the
like.
In a preferred design form of the invention, not only the transport speed of
the processed
items, but also the speed of the coated anodic device itself is used to
achieve an intensive
wiping effect. Depending on requirements and design, a great variety of
effects and wiping
speeds can be achieved.
The aforementioned relative speed may be low, e.g., almost approaching zero.
Furthermore,
in implementing the process according to the invention, pressure can be
exercised by the
wiping device on the items to be processed. In the presence of an elastic
coating on the
wiping device, the coating can be flattened or pressed. Apart from the fact
that irregularities
in the thickness of the items can be smoothed out in this way, this helps to
reinforce the
effect according to the invention of disrupting the diffusion layer. This is
especially true for
the disclosed combination of features.
FROM : TEL: JRN.25. 1995 10:10 RM P18
WC) ')~I/03G55 1'~~ 1'/D1:H3/t)OGBA
further proc-c~cs Inc:asuras prcrntotc thc~ Massage of the elcct.nc~lytc
through the drill holes and
t.lrus the metaliii.at:ic~n of the innrr walls of the drill holes.
1~urtherrnorr., they contribute t.o
cxtractinK from t.hc drill lmles particles or the like pr4sent therein.
The. invention is also based on the; object c~f crcat.ing an arrangement for
the electrolytic
prcreessing c~f printed circuit boards with drillings, which al-c taken by
conveyer means
throu6h a treat.mc.nt 1>ath, or conducted tc~ a t.reatntent station, whcrcsby
means fc~r rcauciog
the thi~knc.ss ~f a metal-ion-depleted r.ono {dlffuslon layer) are provided,
which arc in contact
with the printed circuit hoards, which arrangement achieves flawless
electrolytic processing,
rossiL~lc: with simr~le means, of one or hot:h surfaces of the printed circuit
boards as well as of
the: drillings or drill hc~lcs {hereinafter called "drill holes") located
therein. 'l'his is possible in
particular with the Proctors rneasures according to one or more o!' the
process claims of the
Present. invcntian.
'!'o attain these cibjects and solve these problems, first of a11, the
arranpament has rnsans for
wiping the surface or surfaces of either catholic items or anodic iterns, and
also has nteans for
conducting ehc electrolyte, in a flow roughly vercica) to the plane: of the
items to be: processed,
through the drill holes of the lat.tcr (flooding mcans~, 'This principle of
the invention is to be
ro:tlized in a structurally simple form, as
,"...
WO 94/03655 ~ ~ ~ ~ ~ ~ ~ 1'CT/DE93/00684
will be seen in greater detail in the discussion which follows, particularly
the discussion of the
examples.
Wiping devices with the coating are an especially advantageous design form of
the invention
for mechanical wiping.
It is recommended that the coating be allowed to bear against the surface of
the items to be
processed with a certain pressure force. This is especially advantageous in
processing
conductor paths and drill holes, because the fluid in the drill holes has on
its surfaces a certain
surface tension that is disturbed by this wiping, thus clearing the way for
ions, in order to
form a metal layer (during galvanization) on the surfaces. Such a pressure
force can, for
example, be achieved through spring bearings of the wiping device, especially
the
aforementioned rollers.
Flat items are especially suitable for being conveyed between rollers. Rollers
per se are known
in their structure and their use in units for processing flat objects;
however, they are known
not in this form of wiping rollers according to the principle of the
invention, but only as
conveyor and guide rollers and as squeeze rolls for sealing. The rollers have
the advantage of
their simple and robust structure and insertion into a processing unit. In
contrast to known
conveyor rollers or pressure rollers, however, these wiping rollers with their
coatings have the
function of achieving the discussed mechanical wiping effect, i.e., their
rotational speed deviates
deliberately
12
CA 02141604 2004-04-07
from the transport speed of the items to be processed which bear against them.
At the same
time, these rollers can also be designed as a counter-electrode to the object
to be processed.
The aforementioned deviation in speed can be achieved by means of the
respective values of
the aforementioned speeds and/or their respective directions. At this point,
it should also be
noted that the aforementioned speed deviation and/or relative speed may be
low, almost zero.
Furthermore, the wiping rollers with their coating can mechanically favor the
carrying away
of particles. This is especially true when the rollers are pressed with a
certain pressure force
onto the surface of the items to be processed. In this way, disruptive layers
on the cathode,
such as gas bubbles suspended on the surface, can also be removed.
Further preferred design forms for reinforcing the metallization of the inner
wall of drill holes
consist of means and devices for conveying the electrolyte through the drill
holes (flooding}
with appropriate overpressure or underpressure.
In another aspect, the present invention provides a process for
electrolytically processing a
flat perforated item, comprising the steps of
moving the item in a transport direction to a treatment station where the item
is
contacted with an electrolyte;
continuously mechanically wiping, in the presence of one of a cathodic item
and an
anode, and an anodic item and a cathode, a surface of the item using means for
reducing the
thickness of a diffusion layer depleted in metal ions adjacent the surface of
the item, which
means include a wiping roller extending perpendicular to the transport
direction over the
entire width of the item and in contact with the item; and
moving the electrolyte in a direction substantially perpendicular to a plane
of the item
as the item emerges from the wiping roller so as to direct the electrolyte
only toward the
perforations in the item to convey the electrolyte through the perforations in
the item under
pressure.
13
CA 02141604 2004-04-07
In another aspect, the present invention provides an arrangement for
electrolytically processing
a flat item having through holes and a width, comprising:
treatment means for applying electrolyte to the item;
means for transporting the item through the treatment means in a transport
direction
along a planar transport path;
means for contacting and reducing the thickness of a diffusion layer depleted
in metal
ions adj acent the surface of the item, the reducing means including a wiping
roller arranged
perpendicular to the transport direction, and configured so as to wipe at
least one surface of the
item across the entire width; and
means for conveying the electrolyte only toward the holes in the item under
pressure
in a flow substantially perpendicular to the planar transport path as the item
emerges from the
wiping roller so as to force the electrolyte through the holes.
Further advantages and features of the invention are found in the other
subclaims, as well as
in the description which follows and in the accompanying drawings of possible
designs
according to the invention. The essentially schematic drawings show:
Fig. 1 A depiction, partially in section, of the process according to the
invention in
principle;
Fig. 2 A design for implementing the process or processes according to the
invention, in
front view and partially in section;
Fig 3 The side view associated with Fig. 2;
Fig. 4 A top view of the conveyor device in Figs. 2 and 3;Compared to Figs. 2
to 4, the
following figures are drawn in larger scale.
Fig. 5. The conveyor device according to Line V-V in Fig. 4, in section:
Fig. 6 The Detail VI circled in Fig. 2, in enlarged scale and partially in
section;
Fig; 7 A first example
14
. . ..~r.. ~..~,~~~~..;_~n. , N~. ..~m., ..nn. o . , ..._ . ...._ w.. .
..,..x_ , . _. ~ ..M
~14~ fi0~~
WO 94/03655 PCT/DE93/00684
of the embodiment and arrangement of the wiping rollers;
Fig. 8 A second example of the embodiment and arrangement of the wiping
rollers
and the flooding;
Fig. 9 A third example of the embodiment and arrangement of the wiping
rollers, also
showing the supply and extraction of electrolytic fluid and the flooding;
Fig. 10 A fourth example of the design and embodiment of wiping rollers, as
well and
the supply and extraction of electrolytic fluid and the flooding;
Fig. 11 A fifth example of the embodiment and arrangement of wiping and
carrying
rollers and the supply of electrolytic fluid, as well as the flooding;
Figs. 12, 13 A sixth and seventh example of the invention with wiping and
flooding means;
Fig. 14 An eighth example of the embodiment and arrangement of wiping and
carrying
rollers and the supply of electrolytic fluid, as well as the flooding;
Fig. 15 A ninth example of the invention showing the design of the wiping
rollers and
an associated conduction of the electrolyte, as well as the flooding;
Fig. 16 A further (tenth) example of the invention for achiev ing the flooding
and
CA 02141604 2004-04-07
wiping effect;
Fig. 17 A further (eleventh) example of the invention for achieving the
flooding and
wiping effect.
The diagram in Fig. 1 shows the principle of the invention. In schematic
fashion, Fig. 1
shows the principle of the invention in the case of a cathodic item K with the
area Kl to be
treated and the wiping device W associated with this. This wiping device W has
the anodic
function. The aforementioned wiping device may be wiping rollers according to
the
examples below or may be another wiping device. In any case, the wiping
process is carried
out mechanically. This process may be carned out on an item conveyed through a
series of
treatment baths, i.e., essentially continuously, but it may also be carried
out on an item which
is introduced into one of the treatment stations or into a treatment bath and
processed there.
In the latter case, the wiping operation and the flooding operation explained
below are
discontinuous. In the case of a flat item, either one of its two surface or
both of its surface can
be wiped. At the same time, the electrolyte is conducted through the drill
holes ("flooding").
The examples discussed below will make refer to details of the above sequence.
Figures 2 to 6 show the aforementioned main possibility for use of the
invention, namely, a
bath station of a galvanization unit that is designed according to the
invention, including the
conveyor means for the items to be processed. A series of such bath stations
can be provided
one behind the other, in order to allow processes to be carried out with
various baths.
16
_ , __:
~. '~ ~. ~~ ~ '~ PCT/DE93/00684
\~O 94/03655
The bath container 1 contains a bath liquid, not shown. An item to be
processed which is
introduced in the direction of the arrow 2 is conducted between guide rollers,
conveyor rollers
and the wiping rollers, which will be discussed in more detail below. The item
can be
transported and processed horizontally according to this example of the
invention. After
processing, the item emerges from the unit in the arrow direction 3. In the
areas 4 and 5, only
conveyor and/or guide rollers are present and shown, whereas in area 6, in
addition to any
conveyor and/or guide rollers, there are also wiping rollers according to the
invention. The
wiping rollers are explained in detail in reference to several examples in
Figs. 6 to 12, whereby
Section 6 in Fig. 3 corresponds to the examples in Figs. 7, 8 and 9.
The movement path for the items to be treated has the position and breadth
designated in Fig.
2 as "a." In Fig. 2, the movement direction 2-3 runs vertical to the plane of
projection. In
this example, a conveyor device 7 is located next to the movement path of the
items to be
treated, which uses conveyor means in the form of a clamp 9 to grasp in
clamping fashion a
flat item 8 on a lateral edge 8' and move the item 8 in the movement direction
2-3. Such a
conveyor device is the subject of DE-OS 36 23 481, to the disclosed contents
of which
reference is hereby made. However, the invention is not limited to the use of
a conveyor
device designed in this manner. This lateral grasp of the flat item by the
clamps 9 has a special
advantage, especially in conjunction with the discussed "flooding," i.e.,
pressing or drawing
electrolyte through the drill holes of the item. During flooding, a
corresponding pressure on
the item arises in the flooding direction. The clamps with their firm lateral
grasp on the item
prevent
17
CA 02141604 2004-04-07
the board in question from being pushed by the flooding pressure. The
aforementioned rill
holes and the means for flooding are not shown in Figs 2 to 6, for the sake of
simplicity.
Reference is again made to the examples which follow. A clamp 9, consisting of
two clips
11, forms a conveyer means 10. All conveyor means are attached to a
continuously rotating
conveyer belt 12, 12', which rotates in the direction of the arrow 13 (see
Fig. 4). When the
conveyor means 10 are located on the side of the strand 12' (see Fig. 3) of
conveyor belt, then
the clamps 9 are in the holding position (see the drawing of the left side of
the conveyor
device 7 in Fig. 2). As soon as the conveyor means 10 move out of the area of
the strand 12'
into the upper strand 12 in Fig. 4, the two clips 11 of the clamps 9 are
pulled somewhat apart,
so that a space exists between them (see the right side of the conveyor device
7 in Fig. 2).
This conveyor device moves the items at a particular and if necessary
adjustable speed in the
direction 2-3.
Fig. 5 shows the conveyor device in detail. Fig. 5 illustrates a cross-section
of the conveyor
device along Line V-V of Fig. 4. It can be seen that in the area of the strand
12, through the
ascent of one of the clips 11 of a clamp onto a guide part 29, the associated
clamps 9 are
moved into the open position. In contrast, in the path area of the strand 12',
such a guide part
29 is not present, and the clips of the clamps 9 lie, under the influence of a
pressure spring,
with corresponding clamping force at the edge 8' of the item (transport
position).
Detail VI in Fig. 2, as well as Fig 6, which depicts this detail, partially in
section, show two
wiping rollers 15, which are moved in opposite directions by a drive via a
toothed gear 16, 17.
For this purpose, there are two spur wheels 17, which sit on the axles 13, 14
of the wiping
rollers 15 and mesh with one another. The anodic wiping rollers 15 are
18
''1~ ~ '-~
CVO 94/03655 ~~ x ~ ~ ~ 1'CT/DE93/00684
connected via contact disks 20 and current contacts 19 which slide thereon as
well as by leads
18 to the positive pole of the current source. The cathodic item 8, shown here
only partially,
is connected to the negative pole of the current source (not shown). Each of
the wiping
rollers is, on its outer circumference, provided with a coating 31 of a
material which absorbs
and is permeated by the electrolyte and the metal ions of the electrolyte.
This material should
be elastic and have a certain softness, in order not to damage the surface of
the items during
the course of sliding along. The coating must be chemically resistive against
the electrolyte.
The material preferably used for this is a felt-type plastic, e.g., of
polypropylene. Here the
term "felt-type" refers not to the textile felt, but to a structure of
interwoven components.
Such materials are also known for use in filters. The coating may also consist
of an open-pore
plastic which has good liquid permeability and is friction-proof. This wiping
coating should-
as should wiping coatings of other materials--be elastic, so that during
application to the
surface to be wiped it compresses somewhat and then can return to its original
form. The
aforementioned permeability to fluids is at least necessary when, according to
one of the
following examples, the electrolyte is pressed from the roller interior
through the coating to
the outside, or is drawn in in the opposite direction.
While any drive rollers and/or guide rollers (see Number 3 and 4) which might
be present
have a rotational speed which corresponds in value and direction to the
transport direction
2-3 and the transport speed of the conveyor means 10, the rotational speed
and/or running
direction of the wiping rollers is such that the circumference of the wiping
rollers 15 moves
relative to the respective surface of the transported items 8. In this way, a
wiping effect is
exercised on the surfaces of the items 8 along the entire length of the wiping
rollers 15.
19
WO 94/03655 PCT/DE93/00684
The length of the wiping rollers I S extends across the breadth of the items
to be processed,
which runs at a right angle to the transport direction, i.e., approximately
the amount "a" in
Fig. 2. However, an item of lesser breadth can also be processed, whereby a
partial length of
the wiping device 15 simply goes unused. The level of the electrolytic bath is
indicated with
a broken line by reference number 25, whereby the item to be processed as well
as the wiping
devices are located below the level in the bath fluid. This also holds true
for the other
examples. As the present example shows, it is advisable, or is as a rule
necessary, to process
an item according to the invention on both of its sides or surfaces, i.e., on
the upper surface
in Figs. 2, 3 and 6 as well as on the lower surface, as reflected by the
arrangement of two
wiping rollers 15, which bear against the respective surfaces of an item from
above and from
below. In cases in which only one of the surfaces of an item needs to be
processed, then the
use of one wiping roller suffices in principle. The fact that more than two
wiping rollers can
be used is illustrated by the examples in Figs. 7 to 15.
As a rule, a certain pressure force is recommended between the coatings 31 of
the wiping
rollers and the surfaces of the items to be processed, which pressure force,
for example, can
be applied by a spring 23 pressing in arrow direction 22 and indicated
schematically in Fig. 6.
In order to be able to process items of varying thickness, the upper roller of
the wiping rollers
15 is mounted in a slot guide 24 and can therefore, when there is an increase
in the thickness
of the items to be processed, give way opposite to the arrow direction 22. The
bath level 25
of the electrolyte is higher than the lower edge of the slot. Excess
electrolyte can therefore
run out through the slot guide 24 and a space 26 between the side wall of the
bath container
1 and another externally located wall 27 according to arrow direction 28.
WO 94/03655 ~ ~. ~ ~ ~J ~ ~ PCT/DE93/00684
The rotational speed and/or rotational direction of the anodic wiping rollers
15 at their
contact points with items having a certain transport speed may be altered and
adjusted to the
desired value through a control of the drive unit of the wiping rollers. It is
also possible to
adjust the pressure force of the spring 23 or other pressure means. In this
way, particular
requirements can be matched with the goal of achieving the most extensive
possible disruption
of the diffusion layer on the surface of the items in which ion depletion
usually occurs.
In the description which follows of examples according to the invention in the
design and
arrangement of wiping rollers 15 or wiping parts which act accordingly, only
these
components of the invention, including supply and extraction conduits for the
electrolyte, are
depicted and explained. Of course, this includes conveyor means for the items
and drive
means for the wiping parts as well as current feeds, which are depicted in
Figs. 2 to 6, for
example, and discussed above. In addition to the conveyor means described
there, or instead
of these conveyor means, it is also possible, for example, to provide conveyor
rollers between
every pair of wiping rollers, whereby the cathodic current feed occurs by
means of loop
contacts on an edge area of the items to be processed. If not already depicted
in the drawing,
the items to be processed has drill holes, and means are provided for
"flooding" these drill
holes, i.e., for passing the electrolyte through them.
Basically, the parts located in the electrolytic bath, such as the tube 30 and
the expanded metal
piece or wire screen 32 described below, must consist of a material which is
not attacked in
the bath under the electrolytic conditions. Suitable materials include, for
example, titanium,
titanium coated with platinum, noble metal, noble metal coating or
21
WO 94/03655 ~ ~ ~ ~ ~ ~ ~~ PCT/DE93/00684
noble metal oxides. This can be done, e.g, according to the example in Fig. 7,
in such a way
that wiping rollers in the form of metal tubes 30 are provided with the
aforementioned felt-
type coating 31 and an expanded metal piece 32 located therebetween, which
positively
connects the tube 30 and the coating 31. Instead of the preferred tubular
expanded metal piece
mentioned above, a preferred tubular wire screen that is welded at the wire
crossing points can
also be used or a perforated tube can be provided. In this example, the tube
30 constitutes an
insoluble anode, which does not give off metal itself, but rather has emits
only current. In
this case, the metal to be deposited is located in the electrolyte. However,
it is also possible
to store the metal to be deposited as a soluble anode in the tube 30 or in
another wiping
element. When the items 8 are run through, the coatings 31 are somewhat
compressed. The
electrolyte is supplied according to the arrows 33. This can also be done
under pressure.
Here, too, the electrolyte passes through the drill holes (not shown) of the
board to be
processed. As will be mentioned later (at the end of the description), any
feature or detail
depicted in one of the examples may also be used in the other examples. This
applies
especially to the means for implementing the flooding of the drill holes 42 of
the items to be
processed. This example and the others show that the distance between the
anode (here the
titanium tube 31) and the cathode (identical to item 8) is very small, so that
practically no
scatterings occur.
The example in Fig. 8 resembles that in Fig. 7. However, Fig. 8 shows one of
the possible
designs for allowing the electrolyte to flow through drill holes 42 of the
items to be processed.
For this purpose, the tubes 30 are provided with perforations, which have
several functions.
First of all, the electrolyte in supplied in the tube interior 35 and passed
along through the
perforations 34 to the coating 31. Furthermore, the electrolyte is conducted
from the interior
of the tube 30 through the perforations 34 of the tube
22
WO 94/03655 ~ ~ ~ ~ 6 ~ ~ PCT/DE93/00684
and the wiping coating to the drill holes 42 of the board 8; the electrolyte
then flows through
the latter and reaches the interior of the counter-roller in question, the
tube 30 of which is
likewise provided with perforations 34. The electrolyte in one tube can
thereby be under
pressure from a pump and the electrolyte in the counter-roller located on the
other side of the
items to be processed can be drawn out of the drill holes. In addition, the
perforations 34 can
also serve to ensure that the material of the coating 31 clings within them.
In this preferred
design, only the inner tube 30 and the outer coating 31 are provided. Instead
of the tube 30
with the perforations 34, a tubular expanded metal piece or wire screen can
also be used.
Of course, the wiping coating 31 surrounds the wiping roller 15 in question on
its entire
circumference. This is true for all examples that show wiping rollers. The
wiping rollers are
generally indicated by the reference number 15 and an associated arrow,
regardless of their
somewhat different embodiments.
In the example shown in Figs. 9 to 14, the structure of the wiping rollers is
the same as in Fig.
7, [consisting] namely of an inner tube 30, an expanded metal piece or the
like (see above) 32
and the coating 31 which surrounds the wiping roller and thus the tube 30 as
well.
In the example shown in Fig. 9, the electrolyte is supplied by means of supply
tubes 37 having
perforations or slits 36, which are located above the free space 38 between
two wiping rollers
15. After the electrolyte runs through the intermediate spaces 38, the drill
holes 42 and the
intermediate spaces (39) located thereunder, it is collected by collection
containers 40 and
conducted to a filter pump.
When an upper wiping roller and a lower wiping roller located opposite to one
another are
provided (for example, in the design according to Fig. 9, then, in alternating
fashion, the upper
23
CA 02141604 2004-04-07
wiping roller can be connected anodically and the wiping roller located under
it can be
connected as the cathode, and vice versa. Such a process and an associated
arrangement are
depicted and described in DE 41 06 333 C1.
The example in Fig. 10 also shows wiping rollers 15 in the design according to
Fig. 7 during
the processing of flat items 8, especially printed circuit boards, which are
provided with drill
holes 42. The electrolyte is conveyed with pressure through the slit 41 of a
flow nozzle 63
upward (arrow 43) through the drill holes 42 located thereover and from here
conveyed back
by means of underpressure through the drill holes 42 (arrow 44) located near
the flow nozzle
63. As this happens, a certain pool 45 of electrolyte (with the electrolytic
surface 45') builds
up above the items 8 to be processed, and this pool provides electrolyte to
the coatings of the
two wiping rollers located about the items 8, while the wiping rollers below
the items 8 are
moistened through the electrolytic flows 44 as well as through the electrolyte
flowing across
the edge of the flow nozzle top. The latter electrolyte achieves a high speed
in the narrow gap
between the items 8 and the flow nozzle, as the result of which lower pressure
is created than
exists in the electrolyte above the flat items. This difference in pressure
causes the electrolyte
to be drawn through the drill holes 42. Such an flow nozzle arrangement can be
provided,
alone or in combination with other means which facilitate "flooding" (see the
other examples
in this regard), in order to convey the electrolyte through the drill holes
42.
This means which can be used for the purpose of flooding according to the
invention can also
eliminate diffusion poor layers in the drill holes 42, so that sufficient
metal precipitation takes place on
the inner wall of the drill holes. In addition, the wiping effect of the
coatings of the wiping roller
24
\~~O 94/03655 PCT/DE93/00684
on the upper and bottom sides of the items, disturbs the surface tension of
the fluid columns
located in the drill holes 42, thus supporting the desired effect. As
mentioned earlier, the
process measures and the means for wiping the surfaces of the flat items to be
processed and
for flooding the drill holes 42 of the flat items therefore work together
functionally and
synergistically.
The example in Fig. 11 is a variant of the example in Fig. 10. Here the left
roller pair has an
upper wiping roller 15 and a lower pressure roller 64, and the roller pair
shown on the right
has an upper pressure roller 64 and a lower wiping roller 15. The pressure
rollers can function
as conveyor rollers or support rollers, which accordingly bear with pressure
against the items
to be processed. Each of the anodic wiping rollers 15 wipes, in the sense of
the invention, the
surface of the item 8 which faces it and also wipes, at the same time, the end
of the drill holes
42 which faces it. Furthermore, a flow nozzle 63 is also provided here, as in
Fig. 10. A
sequential galvanization of the drill holes 42 from alternating sides in the
transport direction
2-3 is achieved. The aforementioned conveyor rollers 64, at least on the upper
side of the
item, are designed as rollers which extend across the entire breadth of the
items or the
treatment path, so that the electrolyte becomes blocked up on the items 8,
while the conveyor
rollers on the bottom side of the item may also consist of several disks
arranged on one axis,
between which the electrolyte can flow.
Figures 12 and 13 show further possibilities for the use of a flow nozzle 63.
According to Fig.
12, two pairs of wiping rollers 15 are provided in front of or behind an
arrangement which
has the flow nozzle 63 with the anode 48 arranged therein. The electrolyte
flow enters in
direction 79 through a connection piece 65, passes through a pre-chamber 68
and a distribution
mask 69 with perforations 66, flows (reference number 67)
~t10 94/03655 PCT/DE93/00684
along the anodes 48 consisting of individual pieces, passes through the slot
41 and the nozzle
area 70 as well as through the drill holes 42 of the items 8 downward (arrow
71) into the area
below the items 8. In detail, reference is made here to the disclosed contents
of DE-OS 39 16
693.7. These examples also involve flat and perforated items to be processed,
preferably
printed circuit boards.
Fig. 13 shows a design similar to the arrangement according to Fig. 12, and
the same reference
numbers are used. The difference is that in the object in Fig. 12 the
electrolyte, after passing
through the drill holes 42, flows freely downward, while in the object in Fig.
13, a suction
segment 72 with the housing 75 is provided between this outflow 71 and the
exit of the
electrolyte from the drill holes 42. An underpressure is produced in this via
the suction
connection piece 73, so that the electrolyte, after passing a further anode
48, is drawn into the
space 74 under low pressure and then is extracted from there through the
connection piece 73.
In connection with the object in Fig 13, reference is made to the disclosed
contents of DE-OS
39 16 694.5.
In the examples in Figs. 10 to 13, the flow nozzle 63 extends across the
entire breadth of the
treatment items, i.e., the breadth "a" in the example from Fig. 2. The same
applies for the
space 68 (Fig. 12 and 13), in which the electrolytic fluid enters via a series
of connection pieces
65 arranged one behind the other at a right angle to the items. In the example
in Fig. 13, the
suction segment 72 of the suction side extends likewise across the entire
breadth "a." In these
examples with the flow nozzle 63, it is thus ensured that, according to the
invention, in
addition to the surface treatment of the items 8 through the wiping roller 15,
there occurs an
intensive flowing through of the item drill holes 42 by the electrolyte, which
in fact flows the
entire breadth "a" of the work pieces conveyed in direction 2-3. This type of
intensive
electrolyte flow through the item drill holes 42
26
WO 94/03655 ~ ~ ~ ~ ~ ~ ~ PCT/DE93/00684
and the correspondingly heavier deposit of metallization on the inner walls of
these drill holes,
in combination with the previously described galvanization of the surfaces of
the items due
to the wiping effect, would not be possible in the arrangement according to
the prior art, in
which the electrolytic flow is conducted at great speed parallel to and along
the work piece
surface. In this case, it would not be verifiable in terms of flow engineering
that the
electrolytic flow passed through the drill holes at a right angle to the flow
direction.
The example in Fig. 14 contains a combination of the arrangement of wiping
rollers and
pressure rollers according to the example in Fig. 11, with a conduction of the
electrolyte as
in the example in Fig. 9. The same reference numbers are used as in Figs. 9
and 11. In
addition, lower conduits 37' with exit openings 36' for the electrolyte are
also provided, which
convey the electrolyte upward from below.
The example in Fig. 15 shows a modification of the example in Fig. 15. The
wiping rollers
15 here, analogous to the design discussed in reference to Fig. 8, consist of
an inner tube 30
provided with perforations 34 or a tubular expanded metal piece or a tubular
wire screen in
which the wires are welded at their crossing points, as well as of the
discussed coating 31.
Within the tube 30 which encircles its axis 76, there is a non-rotating supply
tube 77, into
which the electrolyte is introduced in a manner not shown here; the
electrolyte then emerges
through passage openings (e.g. perforations) or passage slots 78 in the wall
of the tube 77
which are arranged one behind the other in the longitudinal direction of the
tube. Of course,
the supply tube 77 with the passage openings or slits 78 extends across the
entire length of the
tube 30 and thus the entire breadth of the items 8 to be processed. The
27
''' 2~~~.~04
WO 94/03655 PCT/DE93/00684
passage openings or slits 78 point with their inlets or outlets toward the
movement path 2-3
of the items 8, so that the electrolyte flowing through these passage openings
or slits 78 of the
supply tube 77 emerges through the perforations (or corresponding slits) 34 of
the tube 30
vertical to the items 8 onto the latter and passes through the drill holes 42.
Thus the flow
speed of the electrolyte through the perforations or slits 78 and the
perforations 34 causes a
corresponding vertical flow through the drill holes 42 of the boards 8 and
therefore also causes
improvement in the metal precipitation there. In this example, the electrolyte
in the supply
tube 77 may either be under pressure and pressed through the perforations or
slits 78 and the
drill holes 42, or else a lower pressure and thus a suction effect is produced
in the interior of
the tube 77, which draws the electrolyte through the drill holes 42 and the
perforations or slits
78. In the latter case, any particles of the wiping coat that have gotten into
the drill holes 42
can be removed and carried away via the tube 77 and later filtered out of the
extracted
electrolyte. Of course, in the example in Fig. 15 as well as in the other
example, a series of
holes 34 are distributed continuously around the circumference of the roller
30. The
aforementioned tube 77 can be located in a wiping roller or above or under the
items to be
processed. Pressure rollers or disks 64 are also shown here, which rotate
around the axis 64'
and serve as support roller or transport rollers for the items 8 conveyed
through.
Fig. 8 shows, schematically, above a flat item 8 provided with~drill holes 42,
e.g., a printed
circuit board, a wiping roller 15 in the form of a flooding anode, which
corresponds to the
parts 30, 31, 77, 78 of the example in Fig. 15. These parts are only indicated
here in schematic
fashion. If a pressure of the electrolyte is formed in the supply tube 77, the
electrolyte flows
downward, according to the
28
1
WO 94/03655 PCT/DE93/00684
arrows, through the drill holes 42. If, on the other hand, an underpressure is
created in the
tube interior 77, then the electrolyte flows opposite to the indicated arrow
direction. This
example shows, as counter or pressure rollers, two counter rollers 48 driven
in the arrow
direction and thus also in the transport direction 3 of the board 8, which
rollers leave such
a broad space 60 free under the perforations or slits 78 of the supply pipe 77-
-and thus in the
flow direction of the electrolyte--that the electrolyte can flow unobstructed
between the
counter rollers 48. l~lonetheless, due to the arrangement of two counter
rollers symmetrical
to the wiping roller 15, even distribution of the pressure of the wiping
roller 15 on the
counter rollers 48 is ensured. These counter rollers are provided on their
surface with
insulation, or else they consist of plastic.
In longitudinal section, Fig. 17 shows the example of a flooding anode shown
only
schematically in Figs. 15 and 16 and identified by the reference numbers 30,
31, 77, 78. The
same reference numbers are used as in Figs. 5, 6, 15 and 16. Reference is made
to the
associated descriptions of these figures. The flooding anode 30, 31, 77, 78
depicted in the
upper area of Fig. 17 can be moved in the vertical direction against the
pressure of springs 23
with its bearings and its drive shaft 49. This permits height compensation, so
that boards 8
of varying thickness can be processed. The current feeds occur via clips 9,
11, which are
connected to one pole of the rectifier and connect the latter to the items to
be processed, as
well as through loop contacts 50, which are connected to the other rectifier
pole and connect
the latter to the drive shaft 49 of the flooding anode.
Furthermore, there is a pressure or counter roller 51 consisting, at least on
its surface, of a
material that is not electrically conductive and provided at its circumference
with drainage
grooves 52, whereby these grooves
29
~~.~:160~~
FROM : TEL: JtatJ.25.1995 10:10 HM P19
WC) 94/03f~55 1'C:T/I~E93/OOG84
farm an angle, hcrt nn acme angle,wit:h the longitudinal axis 53 of Lhls
rollt.r 51. Jn this way,
the tlecarolytt crncrginl; tlrrwnw:trel frc~tn the drill holes 4z iv
c.:onvcyed away. .In this cast, as
tlrc arrows show, the c~lectrrrlyte is conveyed through pressure in arrow
direc.~tion 55 and,
;,cc~ordin~, try the: arr~rws SA, is pawed tlrou~;h t he l,rrfcrraticmx ar
slits 78 and then through the
drill hales 42 and c:c~nduct.ed into the drain;tgc t;roovcs ~2. Instead of
tltis, it. is also possible
far sucaicm to occur at the upper end 77' of the flood tube olpnsite to the:
dircctioo of the
arrrrw 55, by n,ean5 f~~ whic;h the clcctrolyte is dravtrn upward from the
drainage grooves 52
through the holes 7R and apposite to the arrow dirccaion S4. '1'Ite flooding
anode is drivrn
by its shaft 49 in a rcaational direction (see arrow 57) opposite trj t:hc
rotational direction
(;rrrow S8) of the drive shaft 5G of the cotmtc.r roller 5l. 'T'hr, reference
nutnbc:r 50 indicates
a loop contact of the current suprly t:o the; drive shaft ~9. The flooding
anode is cxluippcd at
one end with inn4r and outer sidc~ slide bearings 59 and 59' for the 30 and
the Drive shaft 49,
rrspeccivcly. '!'he aforementioned slide bearings 59, 59' are located nn the
circumference or
on the inner diameter of a seationary bearing shell 79, which is held via a
stay 80 on a frame
crf this ~trrangc~mer,t not described in tnorc detail and is conduct:ad so as
t.o be vertically
movable in a recess 81 by a certain path segment.
1n the case of printed circuit boards in which the drill hole walls arc first
coated only with a
ccmduct.ive layer that cannot tolerate larger' currc~.nt densities, lower
currem densities arc t:o he
used at the beginning in t:hc first part of the processing section G (see Fig,
3). Once a sufficient
mct.al layer has been deposited thercy, then, aS ItL.It7S 1l,UVe through
Section G in direction 2-3,
thr.. current dcnsit:y of the galvanirat.ion process is increased by measures
that arc known in
themselves.
The process and the arrangement according to the invention arc also suitable
for the processing
of flat items
~1~~~0~
WO 94/03655 PCT/DE93/00684
which are suspended vertically in treatment baths and remain there during the
treatment. In
this way, the inventions provides not only for continuous runs of the items to
be processed,
but also for discontinuous operation, in which the items are placed in a
station and undergo
processing there. During this processing, wiping and flooding are carried out.
Thus "periodic"
wiping and flooding take place during the periods of the bath treatment in
question.
All depicted and described features and their combination with one another are
essential to
the invention for different design forms. Features and details described in
one of the examples
can also be used analogously in other examples.
31
