US2993492A

US2993492A - Apparatus for strip treatment

Info

Publication number: US2993492A
Application number: US544564A
Authority: US
Inventors: Gerald H Mains; Leon W Mcginnis; Joseph S Tatnall
Original assignee: National Vulcanized Fibre Co
Current assignee: National Vulcanized Fibre Co
Priority date: 1955-11-02
Filing date: 1955-11-02
Publication date: 1961-07-25
Anticipated expiration: 1978-07-25
Also published as: GB834255A

Description

July 25, 1961 Filed. NOV. 2, 1955 G. H. MAINS ETAL 2,993,492

APPARATUS FOR STRIP TREATMENT 3 Sheets-Sheet l FIG. 2

GERALD H. MAI/VS LEON if. MC GINIVIS 8 JOSEPH 3. TA TAMI. L

IN V EN TORS BY [MM 114% THE/R ATTORNEYS July 25, 1961 G. H. MAINS ETAL APPARATUS FOR STRIP TREATMENT 3 Sheets-Sheet 2 Filed Nov. 2, 1955 GERALD H. MAINS LEON W. MC GIN/W8 8 JOSEPH S. TATNALL INVENTORS J M X THE/RATTORNEYS July 25, 1961 Filed Nov. 2, 1955 G. H. MAINS ETAL APPARATUS FOR STRIP TREATMENT FIG.5

3 Sheets-Sheet 3 cam/.0 H. MAINS LEO/V n: Mc G/N/V/S a JOSEPH S. TATIVALL INVENTORS BY [M Z4? THEIRATTORNEVS United States Patent 2,993,492 7 r, APPARATUS FOR STRIP Gerald H. Mains, Chester County, 'Pa., and Leon W.

McGinnis and Joseph S. Tatn'all, New Castle County, Del., assignors to National Vulcanized Fibre Co., Wilmington, Del., a corporation of Delaware Filed Nov. 2, 1955, Ser. No. 544,564 16 Claims. (Cl. 13457) This invention relates to an apparatus for treating one surface of a moving strip with a liquid treating agent. More particu1arly, the process and apparatus of the present invention accomplish the aforesaid treatment of but one surface of the strip without mechanically contacting either strip surface dnring'the treating operation.

In the art of treatinga strip of metal or other material, it is often desirable to treat one surface wih a liquid treating agent while the opposite surface remains free of contact with the treating agent. It is also found desirable to be able to treat but one surface while avoiding mechanical contact with that surface'as well as the opposite surface. For example, certain products require a uniformity of chemical treatment which will not permit mechanical contact with the treated surface during the treating operation and at the same time, the reverse surface might be highly polished or in some other condition prohibiting mechanical contact during the chemical treatment.

It will be understood by those skilled in the art that although the present invention is described in an environ ment in which one surface of a copper foil is treated in order to improve its characteristics for bonding that surface to a dielectric material for forming a printed circuit, the invention is equally applicable to any liquid contact surface treatment of a liquid treating agent impervious material, particularly when but one surface is to be treat ed and it is desirable to avoid mechanical contact with both surfaces during treatment.

In the manufacture of printed circuits, it is conventional to bond a copper foil to the dielectric material with an adhesive. By a subsequent operation, the circuit pattern is formed on the dielectric-by etching or otherwise removing theu'ndesired areas of copper foil. It is essential that the copper foil be securely bonded to the dielectric. For this :purpose, it is conventional to oxidize the surfaceof the foil which is to be bonded to the dielectric by the use of a liquid treating agent. Among the various methods of oxidizing, one method is to oxidize both surfaces of the copper foil, bond one surface of the copper foil to the dielectric and then reduce the exposed oxidized surface of the foil so that it Will be-suitable for making electrical connection thereto, as by solderiing. This-method, besides requiring anunne'eded oxidation and subsequent reduction of the exposed surface, results in the lossof copper and does not obtain a'conductor circuit of uniform thickness. Other manufacturers have attempted to treat but one surface of the foil. In general, mostof these attempts have been unsuccessful at least to the extent that uniformity of surface oxidation on the desired surface has not been obtained while completely avoiding oxidation of the total area of the reverse side.

Another dilficulty encountered in such prior art treatments is lack of uniformity of treatment, i.e., uniformity of surface oxidation. Lack of uniformity is objectionable because the bonding strength between the foil and dielectric varies from one area to the next. In those areas Where surface oxidation has not been adequate, bonding failures-may occur and as a result an inferior .or defective product is obtained.

Furthermore, since the conductor foil for forming printed circuits may be of the order of 0.001 inch thick- Patented July 25, I961 ice:

ness, strips of this material cannot be continuously'fed through treating apparatus of the aforesaid type without encountering diflicult tracking problems. Thus, uneven windings of the strip on the parent feed roll cause such problems with the result that users of 'the heretofore designed apparatus have found treatment of one surface diflicult if not impossible because the continuously moving strip will not center itself and remain so over the treating zones. Thus, although'many processes of and apparatus for such treatment have been proposed, one of their inherent ditficulties has been the lack of a suitable means to overcome the tracking problem. It will be appreciated that the use of a conventional guiding method where a finger rides against the edge of the copper foil and is in turn connected to a control mechanism for a skew roll is not an effective means of solving the tracking problem because of the fragile nature of this extremely thin. strip.

Accordingly, it is an object of the present invention to provide an apparatus for continuously treating one surface of a strip with a liquid treating agent while avoiding treating agent contact with the other surface of the strip.

Another object of the present invention is to provide an apparatus for continuously treating one surface of a strip with a liquid treating agent while avoiding treating agent contact with the other surface of the strip and simultaneously avoiding mechanical contact with either surface of the strip during the actual treating operation.

Another object of the present invention is to provide an apparatus for obtaining uniformity of treatment of one surface of a moving strip with a liquid treating agent while avoiding contact with the other surface of the strip with the treating agent and simultaneously avoiding mechanical contact with either surface of the strip during the actual treating operation.

Another object of the present invention is to provide an apparatus for continuously treating but one surface of a moving strip as aforesaid wherein proper tracking is obtained while avoiding mechanical contact with the edges of the strip.

These and other objects of the present invention will become more apparent upon considering the following description thereof taken in conjunction with the drawings wherein:

FIG. 1 is a diagrammatic side elevational view of the apparatus of the present inventionpartially in cross-see tion;

FIG. 2 is a top plan view of a portion of FIGCI.

FIG. 3 is a schematic plan view of the novel head of the present invention used for distributing a treating liquid on but one surface of a longitudinally moving strip;

FIG. 4 is a bottom plan view of section A of'the head of FIG. 3 and includes the positioning of the edged the strip with relation to section A of FIG. 3;

FIG. 5 is a schematic view of a circuit diagram forming a portion of a preferred tracking mechanismin accordance with the present invention;

FIG. 6 is a top plan view of the mechanism associated with FIG. 5 and employed for obtaining proper strip tracking; and

FIG. 7 is a cross-sectional view of FIG. 6 taken along the line 7--7,

In accordance with the present invention, it has'been found that it is possible to float a longitudinally moving strip on the surface of a continuous-supply of liquid treating agent without exposing the other surface to liquid contact and while avoiding any mechanical contact with either surface or the edges of the strip 'duringthe actual treatment operation. In addition to this, and as a result of the specific means utilizedfor floating the longitudinally moving strip, uniformity of treatment of the entiretreated surface area results.

With reference to the drawings, particularly FIGS. 1 and 2, the strip is fed from parent coil 12 by means of driving rolls 14 across treating apparatus 16, via idling squeegee rolls 18 across a plurality of washing and rinsing apparatus 20, via idling rolls 22 through drying apparatus 24, and is subsequently rewound under positive tension as coil 26. In order to avoid injury to the strip between treatment operations, rolls 14, 18, and 22 are covered with rubber or another relatively soft non-abrasive material. As shown, apparatus 16 includes reservoir tank 30 open at the top for the purpose of supplying treating liquid. Conduit 32 provides a means for pumping fresh treating liquid via pump 34 and valve 36 to tank 30. Drain conduit 38 and its associated valve 40 provide a means for withdrawing spent treating liquid from tank 30. Conduit 42 leading from tank 30 via pump 44 and valve 46 provides a means for supplying treating liquid under controlled pressure via conduit 48 to distribution means 50. Distribution means 50 which includes bottom and side walls is provided with a top member 52 having a plurality of parallel rows of liquid applying orifices 54 with the rows arranged at an acute angle to the direction of strip movement or travel. Each orifice 54 subtends an incremental width of the strip and has another orifice 54 in the same or a dilferent row subtending a contiguous incremental Width of the strip 10. This particular arrangement of orifices in the top member 52 as will be described more fully hereinafter in connection with FIGS. 3 and 4 permits the liquid supply to head 50 via conduit 48 to float the moving strip 10 on the surface of the liquid by liquid contact with the bottom side of the strip only.

The aforesaid floating action of strip 10 on the liquid streams emerging through orifices 54 is accomplished without the need of any mechanical contact with either the top or bottom surface or the edges of the strip '10. This is an extremely important advantage in that neither surface of strip 10 is afliected by abrasion or other mechanical action, the bottom surface of strip 10 is assured uniformity of treatment over the entire surface area since there is no masking by the presence of any means mechanically contacting the bottom surface of strip 10, and regardless of the thickness of strip 10, particularly when the strip is a foil or other extremely thin material, no mechanical contact means tends to distort or otherwise afiect the strip edges.

Run-off treating agent from the distribution head 50 flows down the outer sides of distribution head 50 and is returned to tank 30. A major portion of the liquid film remaining on the bottom surface of the strip after passage over head 50 is removed by squeegee rolls 18. In view of the fact that the treatment occurring in the area above head 50, which in the case of the described embodiment of the present invention amounts to oxidization of the bottom surface, has already occurred, the subsequent squeegee action of rolls 18 does not interfere with uniformity of treatment.

Apparatus units 20 in the illustrated embodiment comprise a series of rinsing or washing zones and in the particular embodiment illustrated provide for countercurrent flow of rinsing water to wash oif residual treating agent on the surface of the strip coming from apparatus 16 via squeegee rolls 18. Thus, each of the units 20 includes a tank 56 and a distribution head 58 having orifices 60 therein arranged as described in connection with orifices 54 of distribution head 50. The last unit 20 collects overflow washing water from head 58 which is provided from a source of supply via conduit 62, pump 64, conduit 66 and loading valve 68. The overflow from this unit is passed via conduit 70, pump 72, conduit 74 and loading valve 76 to the head 58 of the second or next to the last unit 20. The overflow from this unit collects in the second or next to the last tank 56 and is passed by conduit 78, pump 80, conduit 82 and loading .valve 84 to the head 58 of the first unit 20. The overflow from this treating head flows into its associated tank 56 from which it flows to drain via conduit 86.

The thoroughly rinsed and washed strip then passes through squeegee rolls 22 and, in the event that the washing water used was not sufiiciently hot to flash off and thereby obtain a dry strip, it is passed through a drying unit 24 and then wound as coil 28.

It will be understood that by proper adjustment of valves 46, 68, 76 and 84, strip 10, by virtue of the size and arrangement of orifices 54 and 60, is floated on the surface of the treating or washing liquid without the need of any mechanical supporting means over the areas of the treating and washing or rinsing distribution heads 50 and 58 respectively. A specific working embodiment presented hereinafter and including numerical data will pro vide those skilled in the art with the information necessary for constructing

suitable heads

50 and 58 having orifices 54 and 60 of proper size and arrangement for permitting adjustment of the rate of supply of the treating and washing or rinsing agent to obtain this desired floating action.

Referring to FIGS. 3 and 4 of the drawings, FIG. 3 schematically illustrates the top surface 52 of distribution head 50. The particular head illustrated has been emplayed for treating copper foil of .00135 inch thickness and 13% inch width over a treating length of approximately 6 feet with a strip feed of approximately three feet per minute. The top plan view of section A of FIG. 3

; as illustrated in FIG. 4 includes a plurality of parallel rows 88 of inch diameter orifices 54 arranged at an acute angle of approximately 14.37 to the direction of. travel of strip 10. This particular angular relationship establishes a center-to-center distance in each transverse row 90 of approximately 1 inch and an offset transverse center-to-center distance between adjacent orifices in the same row 88 of approximately A? inch. Since the diameters of orifices 54 are also A; inch, this means that adjacent orifices in a row arranged at theacute angle to the direction of strip movement are tangent to a common line parallel to the direction of travel of the strip. This is illustrated by the line 92 arranged tangent to theadjacent orifices 54' in the upper, left-hand corner of distribution member 52. By virtue of this arrangement, each orifice therefor subtends an incrementalwidth of the strip and has another orifice subtend-ing a contiguous incremental Width of the strip.

It will further be noted in connection with FIG. 3 that there are an even multiple number of orifices 54 lo- 2 cated on each line passing through the center of each 1 90 in sections K and L were not included, there would" orifice of the transverse row and extending in a direction parallel to the direction of strip movement. (Ihus, for example, there are four such orifices along the line 94 of FIG. 4, it being apparent that there are 19 orifices so located along the length of the distribution head 52' as schematically illustrated in FIG. 3. This arrangement is a preferred arrangement in that it provides for uniform coverage of each incremental area of the strip treated. If, in the present illustration, the last two transverserows be but 17 orifices along a given line such as 94 and it would be found that along other lines parallel to that line, there would be a lesser or greater number or orifices. As a result, the increment of width subtended by the 22 widths subtended by orifices located along other lines parallel to that line. As stated, this is a preferred arrangement in that it is an optimum arrangement for equal distribution of liquid over each incremental area. It will, however, be apparent to those skilled in the art that substantially the same number of orifices, e.g. a variation of one or two when 24 orifices lie along a given line, will suflice to obtain a suificient uniformity of treatment to complywith the uniformity requirements in many operations.

The liquid streams emerging through the orifices 54 impinge on the bottom surface of strip 10 and form a liquid pool which floats the strip 10 free of mechanical contact with the top of distribution head 52 and without wetting the top surface of strip 10. In order to provide suflicient surface area on the top of head 52 to form an adequate pool, it is desirable that the orifices be formed in a plate member 52 having two substantially parallel sides 98 arranged parallel to the direction of strip movement and spaced apart a distance greater than the width of the strip. The prescribed arrangement of orifices in such a plate member then forms an orifice-free border on-each parallel side 98 of the plate member. The width of each border should be at least /2 the transverse distance between adjacent parallel rows of orifices for preferred results, i.e., /2 the distance between parallel rows 88 measured in the direction of the transverse row 90.

As previously indicated, the liquid velocity of the stream emerging through each orifice is of importance to the present invention. By the same token, the distance from the bottom surface of the strip 10 to the top surface of the distribution head '52 is also of importance because this distance taken in conjunction with the stream velocity will determine the force with which the liquid treating agent impinges against the bottom surface of the strip 10. It is found that when too high a liquid velocity is employed, the treated bottom surface may display a streaked elfect indicating lack of uniformity of treatment. In the specific form of treatment employed for illustrating the present invention, i.e. oxidization of the bottom surface of a copper foil of 0.00135 inch thickness by the use of a liquid treating agent, the streaked effect is'apparently due to removal of previously formed oxide coating and is therefore attributed to erosion brought about by an inordinately high liquid stream velocity. In this specific embodiment it 'has'been found that with the orifice arrangement specifically described above in connection with FIGS. 3 and 4, control of liquid velocity to obtain a maximum height in the absence of the strip 10 of approximately inch obtains uniformity of surface oxidization without wetting the top surface of the strip while floating the strip at a distance of about inch above the distribution head 52. It will, however, be apparent to those skilled in the art that variations in orifice diameters and arrangements thereof, the nature of the material being treated, the nature of the surface treatment and other factors are controlling for the purpose of obtaining optimum results and these factors are readily determined in view of the teaching contained here- Referencehas been made above to an orifice subtending an incremental-width of the strip and having another orifice subtending a contiguous incremental width. Reference has also been made to preferred arrangements of orifice patterns wherein adjacent orifices in the same acutely arranged row are so arranged that they are tangent to a common line extending in a direction parallel to the direction of strip movement. As stated, this tangential arrangement is a preferred arrangement, it only being necessary that for 'each orifice subtending an incremental width of the strip there is another orifice subtending a contiguous incremental width. Thus the word subtending as used herein and in accordance'with conventional usage also connotes an arrangement of each orifice with reference to some other orifice whereby the areas'are'contiguous by virtue of the inherent increase in size of the cross-sectional area of each emerging stream as it progresses from its emitting orifice. Thus, depending upon the liquid velocity 'as determined by the abovementioned characteristics andthe distance the strip lies above thehead 52, such above-referred to tangential relationship becomes one of approximate tangency insofar as the principles of the present invention are concerned. The preferred arrangement, however, being one in which the tangential relation exists.

Referring to FIG. 5 of the drawings, there is illustrated an electronic detecting-means for sensing improper tracking of the strip 10 which would result in improper centering of the strip 10 over the distribution head 52. As previously stated, the width of the area of the distribution head 52 including orifices therein is less than the widthof the strip 10 passing over the distribution head 52. For this reason-certain lateral variation in the path of strip travel can be tolerated while still obtaining uniformity of treatment without wetting the upper surface-of the strip 10. However, for maximum results, the preferred form of the present invention includes a device such as that shown in FIG. 5 for sensing improper tracking as well as apparatus subsequently to be described in connection with FIGS. 6 and 7 for compensating for the improper tracking as detected by the sensing means ofFIG. 5. Although any form of sensing and compensating device which does not, in the case of the present-=ernbodiment, physically contact the strip will serve the purposes of the present invention, the illustrated form as-shown'in-FIGS. 5-7 is a preferred form of device since it has been found that it is highly effective to the extent that the lateral'excursion may be controlled within the limits of approximately 10.005 inch.

The specific detector means of FIG. 5 employs a detecting head '100 having a slot 102 therein through which one edged the strip10'passes. The strip 10 functions as an electrostatic shieldbetween two

coils

104, 106 positioned on oppositesides'of the slot. These coils are in turn connected inafeed-back loop of oscillator circuit 108 including vacuum tube 110, with the strip 10 arranged to vary the shielding between the two coils and thereby vary the effectiveness of the feed-back. Conductor 112 impresses the negative voltage that develops on the grid of the tube during oscillation, on the control electrode 114 ofrelay tube '116 in the plate circuit of which is connected the windings of relay 118. Armature of this relay is normally biased so that with the relay winding deenergized it completes'a circuit to line 122 but when the relay is energized the armature is pulled away from line 122 and into engagement with the line 124. The armature is itself connected through resistor 126 to the negative terminal 128 of asource of current. In the illustrated construction this terminal is an intermediate point in the circuit 130 that supplies the higher voltage current used to energize the-=oscillator 108.

Line 122' leads to the control electrode 132 of a relay tube 134 in the plate circuit of which are the windings of a second relay 136. 'Between control electrode 132 and the current return-or ground 138, are connected in parallel a charging capacitor and a bleeding resistor 1-42. Relay 136 is arrangedto operate a power relay 144-that energizes electric motor 146 for operation in one direction, asfor example forward, so as to cause the strip 10 to be laterally shifted to the left, as seen in the figure.

In 'a corresponding manner, line 124 is connected to control-grid 152 of a third relay tube 154 for operating a relay 156 that controls a power relay 164 to energize motor 146 in the opposite or reverse direction to cause the sheet 10 to be shifted to the right. A charging capacitor '160 and a-bleeding resistor 162 are also connected between the control electrode 152 and the circuit return.

As's hown, the windings of

relays

118, 136 and 156 are operated by alternating current rectified by the relay tubes and supplied'by an'isolation transformer 170, preferably through a warm-up delay switch 172 that keeps the energizing voltage from the relay tubes when the apparatus is switched on until after a short time delay which permits the tubes to war-m up to operating temperature.

when the edge of strip 10 is too far to the left, the feed-back between the

coils

104 and 106 will cause oscillation of oscillator 108 thereby impressing a negative voltage on control grid 114. This blocks the passage of current through relay tube 116 so that relay 118 is deenergized and armature 120 engages line 122. .The,

negative voltage of source 128-is accordingly applied to control grid 132 of relay tube 134. However, the resistor 126 will cause the voltage to only gradually build up in charging capacitor 140 so that the relay tube 134 is not cut 01f until after an appreciable time delay. After this time delay, the power relay 144 is deenergized and stops motor 146 which could have been moving the strip to the left. Strip 10 will accordingly stop moving to the left.

In the meantime, the same dropping of the armature of line 120 against line 122 was accompanied by a disengagement from line 124. :Capacitor 160, which might have previously been charged, accordingly begins to discharge through its bleeding resistor 162, until the negative voltage is sufiiciently low to permit relay tube 154 to conduct. This conduction energizes the winding of relay 156 which in turn trips power relay 164 to drive motor 146 in the opposite or reverse direction, to move the strip 10 towards the right.

In other words, if the motor 146 is moving strip 10 too far to the left, the apparatus will cause it to stop moving to the left and to start moving to the right. correspondingly, if the strip moves too far to the right, the oscillation feed-back path is blocked sufliciently for the oscillation to stop, permitting relay tube 116 to conduct, thereby returning armature 120 to line 124. The effect of this is to stop the motion of the strip to the right and to start it moving to the left.

A feature of the apparatus of FIG. 5 is that the cutoff delays for

relay tubes

134, 154 can be made shorter than the firing delays of these tubes, as by appropriate adjustment of the resistance 126 with respect to

resistances

142 and 162. Accordingly, the application of the negative voltage from line 128 will fairly rapidly stop conduction through a relay tube and quickly deenergize the corresponding power relay. On the other hand, the disconnection of a control grid from source 128 will cause the charging capacitors to more gradually discharge so that the tubes will not become conductive until the lapse of a longer interval of time. In this way, a slight shift of the strip in one direction will not cause motor 146 to reverse if the shift is promptly followed by a corresponding shift in the opposite direction. For most pratical strip-moving speeds, a time delay of about seven seconds between the actuation of one power relay and the actuation of the other, is very effective and provides the above close tolerance in the position of the strip edge. Longer or shorter delays can also be used to give lesser or greater tolerances, or when the strip is moving exceedingly slowly or very rapidly. It is preferred, however, to have at least a few seconds delay since this is very helpful in keeping the 'motor from hunting, that is continuously switching to an fro too rapidly. Actually theapparatus can then operate with the motor not energized most of the time.

Although thyratrons are shown as relay tubes in FIG. 5, vacuum type tubes can be used instead. Furthermore, the relay tubes can be connected to directly operate the power relays without the intervening

mechanical relays

136, 156, for example. The tubes can also be replaced by transistors, if desired. Instead of using the negative voltage of the oscillator grid, the control for relay tube 116 can be taken from the oscillations themselves which can first be rectified.

Some additional time delay can be obtained from a filter capacitor shunting electrode 114 to ground, but this delay is preferably only a small part of the entire delay.

- As illustrated in FIGS. 6 and 7, the reversible electric motor146 driving through a gear reduction unit 174 and sprocket and chain arrang'ement176 rotates worm shaft 178 mountedin bearings 180. Depending upon the direction of rotation of the reversible electric motor 146 as determined by theposition of strip 10 in slot 102 of detecting head 100, yoke 182 moves to the left or right as viewed in FIG. 6. The fingers 184 of yoke 182 receive the shaft 186 of parent'feed roll 12, shaft 186 being mounted for rotation in and lateral movement through bearings 188. On either side of yoke 182 and adjacent thereto are positioned collars 190 fixed to shaft 186. By virtue of this arrangement, parent feed roll 12 is shifted either to the left or to the right as viewed in FIG. 6 as determined by the direction of movement of yoke 182. The lateral shifting of parent feed roll 12 as delayed by the time delay mechanism permits entry of strip 10 into driving rolls 14 with a'maximum lateral tracking of $0.005 inch while avoiding wrinkling. By this arrangement and proper adjustment of the alignment of rolls 14, 18, 22, and rewind coil 28, even when treating very thin copper coil, the strip 10 moves over the treating heads 52 and 60 with a minimum lateral deviation in its path while eliminating physical contact with the strip during the actual treatment or washing operations and during the sensing operation for assuring optimum tracking.

Although certain numerical data has been given above in connection with the preferred embodiment of the present invention, the following description will serve to completely illustrate the same. A copper foil strip of 13% inches width and a thickness of 0.00135 inch was fed by driving rolls 14 at a speed of approximately three feet per minute and kept under constant tension by the driving action of rolls. An aqueous treating agent containing 1 /2 pounds of a Sato-S mixture of sodium chlorite and sodium hydroxide per gallon of water Was pumped at a rate of approximately 40 gallons per minute via conduit 48 to distribution head 50. A plurality of parallel rows of 4; inch diameter orifices spaced apart a transverse center-to-center distance of one inch and arranged at an angle of approximately 14.37 to the direction of strip movement with a distance of approximately /2 inch between adjacent transversely extending rows of orifices distributed this liquid on the bottom surface of the copper foil. The positioning of the supporting rolls 14, 18 and 22 taken in conjunction with the liquid velocity of the streams emerging from the so arranged orifices floated the strip on a liquid pool whose depth was approximately )1 inch. There were 12 orifices in each transversely extending row 90 and 19 orifices having centers along each line 94. The dimensions of the total area of the distribution head 52 including the orifice-free border was 10 inches by 74 inches. After this treatment, the strip was washed in the countercur rent arrangement illustrated in FIG. 2 in which each orifice head 60 had the same arrangement of orifices except that there were but 7 orifices having centers along a line passing through the center of any one orifice and extending in a direction parallel to the direction of strip movement. Washing or rinsing water fed via conduit 66 to the last distribution head 60 was at a rate of approximately 20 gallons per minute and at a temperature of approximately 205 F. As the result of this washing or rinsing operation, the strip, after emerging from squeegee rolls 22, was dry and free of any detectable residual treating agent salts. Thus, it was unnecessary to employ drying chamber 24. The strip then passed over tension rolls 26 and was rewound as coil 28. Upon examination, the strip was found to be uniformly oxidizedon the bottom surface with no oxidization due to the treating liquid on the top surface. Upon bonding the treated copper foil surface to a dielectric material and etching to form a printed circuit, there were no observed failures of bonding.

We claim:

1. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip, said head having a plurality of equally-spaced-apart parallel rows of liquid-applying orifices, the rows being arranged at an acute angle to the direction of strip movement, and

each orifice subtending an incremental width of the strip, the spacings between orifices being such that adjacent 9 orificesinthe same row subtend contiguous incremental widths of the strip.

2. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 3 wherein there are a substantially even multiple number of orifices located-on each line passing through the center .of each orifice and extending in a direction parallel to the direction of strip movement.

3. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip, said head having a plurality of parallel rows of liquid-applying orifices, the rows being arranged at an acute angle to the direction of strip movement, the center-to-center distance of adjacent orifices in a row being equal substantially to the center-to-center distance of other adjacent orifices in other rows, and each orifice subtending an incremental width of the strip, the spacings between orifices being such that adjacent orifices in the same row subtend contiguous incremental widths of the strip.

4. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 3 wherein there are a substantially even multiple number of orifices located on each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

5. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip, said head having a plurality of equally-spaced-apart parallel rows of liquid-applying orifices, the rows being arranged at an acute angle to the direction of strip movement, the center-to-center distance of adjacent orifices in a row being equal substantially to the center-to-center distance of other adjacent orifices in other rows, and each orifice subtending an incremental width of the strip, the spacings between orifices being such that adjacent orifices in the same row subtend contiguous incremental widths of the strip.

6. A head for distributing a treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 5 wherein there are a substantially even multiple number of orifices located on each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

7. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip, said apparatus comprising means for continuously advancing a strip along a substantially horizontal path, a liquid distribution head arranged below the path of strip travel, said distribution head having a plurality of parallel rows of liquid-applying orifices, said rows being arranged at an acute angle to the direction of strip movement, each orifice subtending an incremental width of the strip and the spacings between orifices being such that for each orifice there is another orifice subtending a contiguous incremental width of the strip, and means for continuously supplying a treating liquid to the distribution head.

8. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 7, including tracking detecting and compensating means arranged along the path of strip movement and before the distribution head, said means operating in the absence of physical contact with the horizontally moving strip.

9. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 7 wherein there are a substantially even multiple number of orifices located on each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

10. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip, said apparatus comprising means for continuously advancing a strip along a substantially horizontal path, a liquid distribution head arranged below the path of strip travel, said distribution head having a plurality of equally- '10 spaced-apart parallel rows of-liquid-applying orifices, the rows being arranged'at an acute angle to the direction of strip movement, the center-to-center distance of adjacent orifices in a row being equal substantially to the centerto-center distance of other adjacent orifices in other rows, and each orifice subtending an incremental width of the strip, the spacings between orifices being such that adjacent orifices in the same row subtend contiguous incremental widths of the strip, and means for continuously supplying a treating liquid to thedistribution head.

11. Apparatus :for distributing treating .liquid on the bottom surface of a longitudinally moving strip as set forth in claim 10 wherein there are substantially even multiple number of orifices locatedon each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

12. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip, said apparatus comprising means for continuously advancing a strip along a substantially horizontal path, a liquid distribution head arranged below the path of strip travel, said distribution head comprising a plate member having two substantially parallel sides parallel to the direction of strip movement, the distance between the parallel sides defining a dimension greater than the width of the strip, a plurality of parallel rows of liquid-applying orifices, said rows being arranged at an acute angle to the direction of strip movement, each orifice subtending an incremental width of the strip, the spacings between orifices being such that for each orifice there is another orifice subtending a contiguous incremental width of the strip, and the positioning of the orifices in each row and the arrangement of rows forming an orifice-free border along each parallel side of the plate member whose width is at least /2 of the transverse distance between adjacent parallel rows of orifices, and means for continuously supplying a treating liquid to the distribution head.

13. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 12 wherein there are a substantially even multiple number of orifices located on each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

14. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip, said apparatus comprising means for continuously advancing a strip along a substantially horizontal path, a liquid distribution head arranged below the path of strip travel, said distribution head comprising a plate member having two substantially parallel sides parallel to the direction of strip movement, the distance between the parallel sides defining a dimension greater than the width of the strip, a plurality of parallel rows of liquid-applying orifices, said rows being arranged at an acute angle to the direction of strip movement, the center-to-center distance of ad jacent orifices in a row being equal substantially to the center-to-center distance of other adjacent orifices in other rows, each orifice subtending an incremental width of the strip, another orifice subtending a contiguous in cremental width of the strip, and the positioning of the orifices in each row and the arrangement of rows forming an orifice-free border along each parallel side of the plate member whose width is at least /2 of the transverse distance between adjacent parallel rows of orifices, and means for continuously supplying a treating liquid to the distribution head.

15. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 14 wherein there are a substantially even multiple number of orifices located on each line passing through the center of each orifice and extending in a direction parallel to the direction of strip movement.

16. Apparatus for distributing treating liquid on the bottom surface of a longitudinally moving strip as set forth in claim 7, said apparatus further including strip tracking detecting and compensating means including a sensing structure positioned to detect and indicate lateral variation in the strip movement and compensating mechanism connected to the sensing structure and the advane ing means to shift the strip laterally in a direction opposite to the variation indicated by the sensing structure, said detecting and compensating means including time delay elements inserted in said connection to delay the shift and enable a spontaneous compensating alignment variation to prevent the shift.

References Cited in the file of this patent UNITED STATES PATENTS 2,264,885 Mueller Dec. 2, 1941 12 Reed Mar. 23, 1943 Dishauzi Nov. 16, 1943 Bond May 11, 1948 Walters Nov. 25, 1952 Abbott Dec. 23, 1952 Hufi Aug.'18, '1953 Campbell Sept. 1, 1953 Cherigie Dec. 13, 1955 Reher Mar. 6, 1956