Apparatus for the galvanic deposition of metal

An arrangement is disclosed for the galvanic deposition of metal at relatively greater speed and with controllable layer-thickness distribution, of the type composed of an electrolysis tank with overflow, electrodes, nozzles, connecting conduit tubes, pumps, control system means and dosaging system means as well as electrical appurtenances, wherein a cathodically-connected work piece to be galvanized is arranged between two nozzles which are each formed from two chambers located one above the other and having separate entrance and exitways, the upper chamber contains an electrolyte exit opening provided as a longitudinal slit and the lower chamber defines an anode niche displaying at the height of the slit a vertically-adjustable opening. Also disclosed is a method for the electrolytical deposition of metal, employing substantially the above described arrangement and particularly for depositing nickel- or gold-coatings on plug contacts of printed circuits.

BACKGROUND OF THE INVENTION 
The invention concerns an arrangement for the galvanic deposition of metals 
at superb velocity and with controllable layer-thickness distribution. 
In general, such arrangements include an electrolysis unit with overflow, 
electrodes, nozzles, connecting conduits, pumps, control systems and 
dosaging systems, as well as electrical appurtenances. 
Also a part of the present invention is a method for the continuous 
galvanization of metal surfaces by way of employment of the same such 
apparatus. 
Work pieces or so-called substrates, i.e., particularly the contacts of 
conductor plates, are galvanically metallized as a rule in throughput 
plants using conventional baths. 
The metallization follows, for the most part, partially, in that plating 
liquid is led against the work pieces respectively plates provided in a 
series by way of a transportation arrangements. 
As a result of the throughput times involved therewith, working up must be 
performed with strong flowing and of sufficient electrolyte supply, which 
leads in the main to unsatisfactory layer-thickness distributions. 
As set forth in German D.E.-0.S. No. 2928904, an arrangement is already 
known for the plating of output leads of a printed conductor plate, 
whereby the plating liquid is led from the reservoir through bore holes 
behind which are applied a foil, even a crimped or bent foil; indeed 
according to the radius of which is the required concentration of liquid 
elevated or decreased. There is generally, no assurance that the 
layer-thickness distribution can be precisely controlled. Moreover, the 
obtained layer-thicknesses do not always correspond to the specifications 
required. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide an 
arrangement of the abovedescribed type, which guarantees a galvanic 
deposition of metals at superior velocity and with controllable 
layer-thickness distribution. 
This object is obtained according to the present invention, by means of an 
arrangement of the general type, having an electrolyte tank with overflow 
means, electrodes, nozzles, connecting conduits, pumps, control system 
means and dosaging system means as well as electrical appurtenances, which 
is thereby characterized by providing to arrange the work piece that is to 
be subjected to the electrolysis-type cathodic layering between two 
nozzles, the said same being always formed of two superposed chambers and 
having separate introduction and exit connection means, the uppermost of 
said two containing an electrolyte exit opening provided preferably as a 
longitudinal slit, while the lower said chamber is being provided with an 
anode niche, which displays a vertically adjustable opening at the height 
of the slit. 
The novel features which are considered characteristic for the invention 
are set forth in particular in the appended claims. The invention itself, 
however, both as to its construction and its method of operation, together 
with additional objects and advantages thereof, will be best understood 
from the following description of specific embodiments when read in 
connection with the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
It is preferable for the arrangement according to the present invention 
that: 
The lower chamber be provided with a niche-shaped construction through 
which the applied insulated anodes are projected into the chamber; 
The nozzles should be disposed so as to be vertically adjustable; 
An adjustable opening displayed by the lower chamber have a cross-section 
substantially between about 300 and 2500 mm.sup.2 ; 
The exit openings for the nozzles should be located close to the work 
piece; 
The work piece should be arranged at a relative interval of approximately 
10 mm.sup.2 from the nozzles; 
The exit opening for the upper chamber is directed at an acute angle to the 
surface of the work piece; 
The arrangement should be disposed both vertically and horizontally 
adjustable relative to the work piece; and 
Supplementary unit means be provided for transport of the work piece in a 
longitudinal direction through the electrolysis tank. 
Regarding the method set forth in the claims, the invention also 
encompasses a continuous electrolytic deposition of work pieces, 
particularly so-called plug-and-socket type contacts of conductor plates 
(printed circuits) for which in particular the abovedescribed arrangements 
is designed. 
The method of the invention includes electrolytic deposition of nickel- or 
gold-coatings at the plug-and-socket contacts of the printed circuits. 
The electrolysis is generally performed with flow densities ranging between 
about 10 and 100 A/dm.sup.2. Preferably, however, flow densities between 
20 and 60 A/dm.sup.2 are employed. 
Flow velocities for the electrolyte vary within broad limits, i.e., between 
approximately 0.1 and 100.0 m/S. Preferably, these values range from about 
1.0 up to 3 m/S. 
A further consideration in electrolysis techniques is the pressure at which 
the electrolyte comes in contact with the work piece. That is, it has 
proven to be advantageous according to the present invention for an excess 
pressure to be provided. Preferably this excess pressure runs from about 
0.8 and 1.0 bar. 
Both the arrangement and the method according to the present invention 
enable a deposition of pore-free precipitant with uniform layer-thickness 
and at improved deposition velocity, it further advantageously following 
therefrom that the thickness is thereby controllable. 
It is an additional advantage according to the present invention that 
soluble anodes are employed. In this manner, the otherwise necessary 
replenishment of toxicologically unfavorable nickel carbonate is avoided. 
In addition, the present invention enables metallization of 
optionally-shaped work pieces. It goes without saying, however, that even 
insoluble anodes can similarly be employed according to the present 
invention. 
The method and apparatus according to this invention are suitable in 
particular for the electrolysis of nickel and gold on to the 
plug-and-socket type contacts of printed circuits during a continuous 
operation. 
Electrolyte compositions of all known types can be employed as the bath. 
Preferably though, it is e.g., conventional nickel- and gold-baths that 
are employed. 
The nozzle means are composed of two chambers having separate entranceways, 
which project into the electrolysis vat filled up to the level of the 
adjustable overflow. The upper chamber is formed as an electrolyte nozzle 
with the outer electrolyte lead-ins and the there-located adjustment 
arrangement as well as the longitudinal nozzle slit inclined downwardly to 
the work piece. The lower chamber is formed by means of an opening of the 
anode apertured chamber, vertically adjustable width height and directed 
to the cathodically-layered work piece; it is into this opening that the 
applied insulated and soluble or insoluble anodes project. Both chambers 
have separate lead-in conduits, a feature of particular advantage when the 
strong electrolyte introduction is not effected directly to the anode 
space. Moreover, the anode projecting into the anode niche do not come 
into contact with the elctrolyte in the electrolyte nozzle. 
The manner of operation of the arrangement is provided by an optimal 
adjustment of both chambers to the bren point of the surface to be 
galvanized of the work piece. Expediently, this purpose is achieved by 
adjustment of the ideal height of the nozzles at the adjustment 
arrangement of the electrolyte inlet and the slit height of 
anode-apertured chamber by means of two spindles during the operation of 
the arrangement above the machine table by means of graduated adjustments. 
With an employment of soluble anodes the possible silting up of the 
anode-apertured chamber can be avoided advantageously by leading the anode 
sediment steadily with the current through a neighboring run-off canal 
into the supply container. The neighboring run-off canal--in connection 
with the main run-off--is relatively small and this operation is promoted 
by the injector effect of the main run-off. 
The selection of materials capable of being employed in the work piece is 
not limited by the specifications of the method, or for that matter, 
apparatus according to the present invention. All customary materials can 
be employed to the extent that they are durable against the activity of 
the baths to be employed. 
Control of the arrangement can be effected by means of electronic systems, 
whereby the arrangement itself can exist as a component of an 
automatically-operated plant embracing transportation arrangement means 
and control systems means. 
In the drawings the following reference numerals are employed: 
1. Electrolysis vat 
2. Overflow 
3. Upper chamber 
4. Electrolyte lead-in 
5. Adjustment arrangement 
6. Nozzles slit 
7. Lower Chamber 
8. Anodes 
9. Adjustable opening 
10. Spindles for adjustment of the slit height of the lower chamber 
11. Niche-shaped construction for the anodes. 
12. Work piece 
13. Main run-off 
14. Neighboring run-off 
15. Machine table 
16. Bath window 
17. Right worm 
18. Left worm 
It will be understood that each of the elements described above, or two or 
more together, may also find a useful application in other types of 
electrolysis techniques, differing from the types described above. 
While the invention has been illustrated and described as embodied in 
apparatus and method for the galvanic deposition of metals, it is not 
intended to be limited to the details shown, since various modifications 
and structural changes may be made without departing in any way from the 
spirit of the present invention. 
Without further analysis, the foregoing will also fully reveal the gist of 
the present invention, that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features, that 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.