CN112708920A

CN112708920A - Fluid delivery system and method of plating a workpiece

Info

Publication number: CN112708920A
Application number: CN202011133675.5A
Authority: CN
Inventors: 韩保罗
Original assignee: Process Automation International Ltd
Current assignee: Process Automation International Ltd
Priority date: 2019-10-24
Filing date: 2020-10-21
Publication date: 2021-04-27
Also published as: KR20210049687A; TWI831852B; TW202117092A

Abstract

Disclosed is a fluid delivery system for an electroplating system, comprising: a tank adapted to contain a fluid; a first fluid transporter having a first fluid outlet for delivering fluid into the tank, a second fluid transporter having a second fluid outlet and a third fluid transporter having a third fluid outlet for delivering pressurised fluid into the tank in oppositely facing directions, the tank having an axis along which a workpiece can move relative to the tank along the axis between the second and third fluid outlets, the second fluid transporter being adapted to deliver pressurised fluid out of the second fluid outlet to exert first and second repelling forces on the workpiece offset from the axis towards the second fluid transporter by first and second distances, moving the workpiece towards the third fluid transporter, wherein the first repelling force is greater than the second repelling force and the first distance is greater than the second distance.

Description

Fluid delivery system and method of plating a workpiece

Technical Field

The present invention relates to a fluid delivery system for use in a tank, particularly a process tank in an electroplating system, and a method of electroplating a workpiece.

Background

In conventional electroplating machines, a plurality of workpiece carriers are movable through and relative to a tank containing a processing solution (e.g., an electroplating solution). Each workpiece carrier is releasably engageable with a respective workpiece to be plated. The workpiece carriers may be moved continuously through the cassettes, i.e. in line one after the other, thereby continuously moving the workpieces through the cassettes. The workpiece to be plated is generally rectangular and planar in shape. When the workpiece is engaged with and carried by the workpiece carrier, the workpiece is oriented vertically and the opposite major surface of the workpiece faces laterally. Therefore, the electroplating machine is called a vertical continuous electroplating machine.

The cathode bars are fixed relative to a box of the electroplating machine, and each of the workpiece carriers is electrically connected with the cathode bars via respective sliding contacts so as to be electrically connected with the cathode bars during movement of the workpiece carrier through and relative to the box. A plurality of anode plates, each powered by a respective power source, are disposed within and fixed relative to the housing. Thus, when the workpieces are moved by the workpiece carrier through the electroplating solution in the tank, they are subjected to the electric field between the cathode bar and the anode plate, causing metal in the electroplating solution to deposit on the workpieces.

It is well known that plating tanks in continuous platers can be as long as 30 to 40 meters, and that the effective coverage area of such platers can be as short as the width of the workpiece. Since the conductivity of the workpiece is primarily dependent on the uniformity of the plating thickness plated onto the workpiece during the plating process, it is important to ensure that the major surfaces of the workpiece do not physically contact any other components within the tank. However, in conventional electroplating machines, it is difficult to avoid disturbances in the movement of each workpiece through the tank because during electroplating the fluid jet (e.g., a jet of electroplating solution) ejected from the nozzle operates in a net momentum-conserving manner at any point along the jet axis and thus applies a small force to the workpiece regardless of the position of the workpiece. Even if the workpiece is held on the center line by guides or rollers in the cassette, these guides or rollers inevitably come into sliding contact with the workpiece at some points, thereby adversely affecting the plating quality.

It is therefore an object of the present invention to provide a fluid delivery system for an electroplating machine and an electroplating method in which the above disadvantages are alleviated or at least provide a useful alternative to the commercial and public. In particular, it was found that the above mentioned drawbacks can be at least alleviated by further improvements and innovations based on existing automated plating systems.

Disclosure of Invention

According to a first aspect of the present invention there is provided a fluid delivery system for an electroplating system comprising at least a tank adapted to contain a fluid, a first fluid transporter having a first fluid outlet for delivering fluid into the tank, a second fluid transporter having a second fluid outlet and a third fluid transporter having a third fluid outlet for delivering pressurised fluid into the tank in opposite directions, the tank having an axis along which a workpiece is movable relative to the tank between the second fluid outlet and the third fluid outlet, wherein the second fluid transporter is adapted to deliver pressurised fluid out of the second fluid outlet to exert a first repelling force on a workpiece offset from the axis towards the second fluid transporter by a first distance to move the workpiece towards the third fluid transporter, wherein the second fluid transporter is adapted to transport pressurized fluid away from the second fluid outlet to exert a second repulsive force on the workpiece offset from the axis to the second fluid transporter by a second distance to move the workpiece toward the third fluid transporter, wherein the first repulsive force is greater than the second repulsive force.

According to a second aspect of the present invention there is provided a method of electroplating at least one workpiece, comprising the steps of (a) delivering fluid into a tank from a first fluid outlet of a first fluid transporter, (b) delivering pressurised fluid into the tank in opposite directions from a second fluid outlet of a second fluid transporter and from a third fluid outlet of a third fluid transporter, (c) moving the workpiece relative to the tank along an axis between the second fluid outlet and the third fluid outlet, (d) applying a first repelling force to a workpiece offset from the axis towards the second fluid transporter by a first distance to move the workpiece towards the third fluid transporter, and (e) applying a second repelling force to a workpiece offset from the axis towards the second fluid transporter by a second distance to move the workpiece towards the third fluid transporter, wherein the first repulsive force is greater than the second repulsive force and the first distance is greater than the second distance.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a fluid delivery system according to an embodiment of the present invention;

FIG. 2 is a side view of the fluid delivery system of FIG. 1;

FIG. 3 is a partial end view of the fluid delivery system of FIG. 1;

FIG. 4a is an end view of the fluid delivery system of FIG. 1;

FIG. 4b is another end view of the fluid delivery system of FIG. 1;

FIG. 5a is a front view of a nozzle of a fluid delivery system according to an embodiment of the present invention;

FIG. 5b is a cross-sectional view of the nozzle taken along line F-F of FIG. 5 a;

FIG. 5c is a schematic side view of the nozzle of FIG. 5A;

FIG. 5d is a schematic perspective view of the nozzle of FIG. 5A;

FIG. 5e is a perspective view of the nozzle of FIG. 5A;

FIG. 6 is a schematic perspective view showing the connection between the nozzle and the pressurizing nozzle;

FIG. 7a is a schematic view showing the workpiece being significantly offset from the central axis of motion through the process tank;

FIG. 7b is a schematic view showing a workpiece with a small offset from the central axis;

FIG. 7c is a schematic view showing the workpiece aligned within the central axis;

FIG. 8 is a graph of repulsive force versus gap distance between the nozzle and the workpiece at two different flow rates;

FIG. 9a is a schematic diagram showing physical contact between the nozzle outlet and the workpiece when the nozzle is not flowing;

FIG. 9b is a schematic diagram showing a small gap distance between the nozzle outlet and the workpiece when the nozzle delivers a small flow;

FIG. 9c is a schematic diagram showing a large gap distance between the nozzle outlet and the workpiece when the nozzle delivers a large flow rate; and

FIG. 10 is a graph showing the repulsive force of the nozzle outlets of three different configurations.

Detailed Description

A schematic diagram of a vertical continuous plating machine according to an embodiment of the invention is shown in fig. 1 to 4b and is generally indicated at 10.

The electroplating machine 10 includes a tank 12 for containing an electroplating solution. The plurality of workpieces 14 are preferably formed together into a continuous and rollable material that is continuously movable in a series through and relative to the housing 12. Each workpiece 14 to be plated is releasably engaged for physical and electrical connection with the workpiece carrier 15, thereby establishing physical and electrical connection therewith.

The electroplating machine 10 includes a fluid delivery system 100. The fluid delivery system 100 includes two opposing rows of

nozzles

110a, 110b for delivering electroplating solution into the tank 12, the nozzles 110a being fixedly spaced from each other. Similarly, the nozzles 110b are also fixedly spaced apart from each other. The workpieces 14 are continuously movable through the tank 12 in series between the

nozzles

110a, 110b such that a first major surface of each workpiece 14 faces the outlet of the nozzle 110a and a second opposite major surface of each workpiece 14 faces the outlet of the nozzle 110 b.

During operation of the electroplating machine 10, the workpiece 14 may move along the central axis 16 while oscillating substantially perpendicular to the axis. For example, the workpiece 14 may oscillate between a first position in which the workpiece 14 is coaxial with the axis 16 and a second position in which the workpiece 14 is offset from the axis 16, which oscillation is highly undesirable because the workpiece 14 inevitably contacts some physical object within the tank 12, particularly the

nozzles

110a, 110 b. Such plating performance is undesirably affected.

The fluid delivery system 100 also includes two rows of nozzles, namely a row of second nozzles 120 and a row of third nozzles 130, for compressing the plating solution to a higher pressure and delivering the pressurized plating solution into the tank 12, the

nozzles

120, 130 preferably being positioned on opposite sides of the workpiece 14 and delivering the pressurized plating solution in opposite directions toward each other and toward opposite major surfaces of the workpiece 14.

Referring now to fig. 5A to 5E, the structure of the

nozzles

120, 130 will be described in detail, each nozzle 120 including a fluid inlet 121 for receiving a plating solution and a fluid outlet 122 for delivering the plating solution to the tank 12, the fluid inlet 121 having a circular cross-section and the fluid outlet 122 having an annular area. The nozzle 120 further comprises a flow path 123 for fluidly communicating the fluid inlet 121 and the fluid outlet 122. The cross-sectional area of the flow path 123 converges from a larger cross-sectional area of the fluid inlet 121 to a smaller cross-sectional area of the fluid outlet 122. First, the plating solution is introduced into the nozzle 120 through the fluid inlet 121 at a first speed, and is discharged through the fluid outlet 122 at a second speed higher than the first speed after passing through the internal flow path 123.

The fluid outlet 122 also includes an annular opening 124, i.e., an annular space at the end of the flow path 123. The annular opening 124 may be bounded by an outer perimeter 125 and an inner perimeter 126. The annular opening 124 need not be provided in an annular shape, and the outer periphery 125 and the inner periphery 126 may be provided in different shapes. For example, the outer perimeter 125 and the inner perimeter 126 may be individually selected from any trigonometry (trigonometry), such as circular, triangular, polygonal, or even any irregular shape.

The annular opening 124 may extend through a flow path 123 formed between the fluid inlet 121 and the fluid outlet 122. In particular, the annular channel may be formed by a cylindrical stop member (stopper member)127 positioned along the flow path 123. The stop member 127 stabilizes the pressure along the flow path 123 and increases the pressure of the pressurized fluid at the fluid outlet 122. In order to maintain a stable flow, the stopper member 127 is preferably provided at a central portion of the flow path 123. That is, if the nozzle body 120 and the stopper member 127 are both cylindrical, the nozzle body 120 and the stopper member 127 are concentrically arranged.

Referring to an exemplary embodiment shown in fig. 6, the first nozzle 110a and the second nozzle 120 are connected upstream to a common fluid pipe 140, and on the other hand, the first nozzle 110b (not shown in fig. 6) and the third nozzle 130 on the opposite side are connected to another common fluid pipe 150. The diameters of the second nozzle 120 and the third nozzle 130 are larger than the diameters of the

first nozzles

110a, 110 b. The second nozzle 120 and the third nozzle 130 are closer to the workpiece 14 than the

first nozzles

110a, 110 b. Thus, the flow at the fluid outlet 122 of the second nozzle 120 and the flow at the fluid outlet of the third nozzle 130 will be greater than the flow at the outlets of the

nozzles

110a, 110 b.

For example, fluid flow is introduced through

inlets

142, 152 of

fluid tubes

140 and 150, respectively. The lower velocity fluid stream is discharged through the outlets of the first nozzles 110A and 110b, respectively. The higher velocity fluid stream is discharged through the outlets of the second and

third nozzles

120, 130. Preferably, the second nozzle 120 and the third nozzle 130 are each located between two

first nozzles

110a, 110b spaced apart from each other by a minimum distance.

Referring to fig. 7a to 7c, the fluid enters the fluid inlet 121 at a relatively low velocity with a high static pressure. Subsequently, the fluid is accelerated to a higher velocity by pressure drop (due to Bernoulli's theorem) and exits the fluid outlet 122 through an annular open area 128 (i.e., 2 rr) formed between the circular flange of the fluid outlet 122 and the workpiece 14. Theoretically, the resulting static pressure of the fluid exiting the fluid outlet 122 must be equal to the pressure of the external fluid in the tank 12, so the pressure of the fluid upstream of the annular opening 124 is higher than the pressure of the external fluid, and this pressure differential creates an "air cushion layer" (cushinon) therebetween. Thus, the gas cushion layer exerts a repulsive force on the workpiece 14 that depends on the pressure difference between the fluid escaping at the fluid outlet 122 and the external fluid pressure.

The inventors have also devised, through their own studies, that the repelling force applied to the workpiece 14 is inversely related to the respective gap thicknesses t between the

fluid outlets

122, 132 and the workpiece 14. The disturbance of the workpiece 14 from the axis 16 to one of the

nozzles

120, 130 will reduce the annular region 128 and in turn increase the fluid velocity through the annular opening. Based on bernoulli's theorem, the upstream pressure will increase with the square of the velocity provided, and also increase inversely with the square of annular region 128. Thus, the closer the workpiece 14 is positioned relative to the fluid outlet 122, the greater the area of the annular opening 128 is reduced and the greater the repulsive force exerted on the workpiece 14.

In use, the workpiece 14 may be moved along the axis 16, and due to the flow of the

first nozzles

110a, 110b, the workpiece 14 will be offset from the axis 16. The workpiece 14 is movable along the axis 16 between the second fluid nozzle 120 and the third fluid nozzle 130, and is offset from the axis 16 by the flow of fluid delivered by the

first nozzles

110a, 110 b. Referring to FIG. 7a, the workpiece 14 having the larger offset d1 from the axis 16, i.e., the smaller gap t, exerts a repulsive force F1 by the pressurized fluid delivered from the second fluid outlet 122 and movable toward the third fluid outlet 132. Alternatively, as shown in FIG. 7b, a workpiece 14 having a small offset d2 from the axis 16, i.e., a large gap t, exerts a nominal repulsive force F2 by pressurized fluid delivered from the second fluid outlet 122 and movable toward the third fluid outlet 132. If the workpiece 14 is positioned substantially in-line with the axis 16, i.e., without offset, as shown in FIG. 7C, the pressurized fluid delivered from the second fluid outlet 122 will not exert any additional or at most negligible force on the workpiece 14.

In addition, the inventors have also devised that the repelling force exerted on the workpiece 14 is related to the flow rate of the

nozzles

120, 130. This is illustrated in fig. 8, which shows the repulsive forces applied to the workpiece 14 at different gap thicknesses between the

nozzles

120, 130 and the workpiece 14, and generally, the larger the flow rate of the pressurized flow directed at the workpiece 14, the larger the repulsive forces applied to the major surfaces of the workpiece 14.

Reference is now made to fig. 9a, 9b and 9c, which are for three different configurations in which the second and

third nozzles

120, 130 operate at different flow rates. If the nozzle 120 provides zero flow, the distance of action between the nozzle outlet and the workpiece 14 is negligible and may even be as low as zero distance due to the jetting momentum of the first nozzle 110b in the opposite direction (see FIG. 9 a). If the nozzle 120 provides a small flow, the distance of action between the nozzle outlet and the workpiece 14 is small, for example 2mm (see fig. 9 b). Finally, if the nozzle 120 provides a larger flow rate, the working distance between the nozzle outlet and the workpiece 14 is larger, for example 4mm (see fig. 9 c).

The second and

third nozzles

120, 130 should be spaced apart from each other by a desired gap distance. If the second and

third nozzles

120, 130 are spaced a small distance from each other, the repelling force exerted by one nozzle, e.g., 120, on the workpiece 14 will be excessive and push the workpiece 14 through the axis 16 and toward the other nozzle 130. If the second and

third nozzles

120, 130 are spaced from each other by too great a distance, the repulsive force exerted by one nozzle 120 on the workpiece 14 will be insignificant and insufficient to urge the workpiece 14 toward the axis 16 and compensate for the offset. Most preferably, the second and

third nozzles

120, 130 should be disposed between a gap distance slightly wider than the thickness of the workpiece 14 so that the offset of the workpiece 14 from the axis 16 will be compensated by the pressurized flow of the

fluid outlets

122, 132 from two opposite directions.

The repulsive forces generated by each of the three different configurations are also shown in fig. 10, where the performance of the two outlets 122A, 122B with the stop member 127 is compared to the performance of the outlet 122C without the stop member 127 (control experiment). Generally, if the stop member 127 is removed from the fluid outlet 122, the performance of the outlet 122 is significantly degraded.

It is to be understood that the foregoing is merely illustrative of examples in which the invention may be practiced and that various modifications and/or alterations may be made thereto without departing from the inventive concept.

It is also to be understood that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Claims

1. A fluid delivery system for an electroplating system, comprising:

at least one tank adapted to contain a fluid,

a first fluid transporter having a first fluid outlet for delivering the fluid into the tank, a second fluid transporter having a second fluid outlet, and a third fluid transporter having a third fluid outlet, the second and third fluid transporters for delivering pressurized fluid into the tank in oppositely facing directions, the tank having an axis along which a workpiece can move relative to the tank between the second and third fluid outlets,

wherein the second fluid transporter is adapted to transport pressurized fluid away from the second fluid outlet to exert a first repelling force on the workpiece offset from the axis toward the second fluid transporter by a first distance to move the workpiece toward the third fluid transporter,

wherein the second fluid transporter is adapted to transport pressurized fluid away from the second fluid outlet to exert a second repulsive force on the workpiece offset a second distance from the axis toward the second fluid transporter to move the workpiece toward the third fluid transporter,

wherein the first repulsive force is greater than the second repulsive force, and the first distance is greater than the second distance.

2. A fluid delivery system as claimed in claim 1 wherein the pressure of the pressurised fluid at the second and/or third fluid outlet is in an inverse relationship to the distance between the second and/or third fluid outlet and the workpiece.

3. The fluid delivery system of claim 1, wherein pressurized fluid at a first velocity is delivered to the workpiece offset from the axis by the first distance and pressurized fluid at a second velocity is delivered to the workpiece offset from the axis by the second distance, wherein the first velocity is lower than the second velocity.

4. The fluid transfer system of claim 1, wherein the second and third fluid conveyors each further comprise a fluid inlet through which the fluid is introduced at a lower velocity and is transferred at a higher velocity to the tank through the second and/or third fluid outlets, respectively.

5. A fluid delivery system as claimed in claim 1 wherein the open area of the second and/or third fluid outlets is in an inverse relationship to the distance between the second and/or third fluid outlets and the workpiece.

6. The fluid transfer system of claim 4, wherein the second and/or third fluid transporters each further comprise a stop member located at the central portion and extending along a flow path formed between the fluid inlet and the fluid outlet.

7. The fluid delivery system of claim 6, wherein the stop member is adapted to stabilize pressure along the flow path and increase the pressure of the pressurized fluid at the fluid outlet.

8. A fluid delivery system according to claim 1, wherein the second fluid outlet and/or the third fluid outlet each comprise an annular opening.

9. The fluid delivery system of claim 8, wherein the annular opening is formed by an outer periphery and an inner periphery.

10. The fluid delivery system of claim 9, wherein the outer perimeter and the inner perimeter have different shapes.

11. The fluid transfer system of claim 1, further comprising a plurality of sets of the second and third fluid transporters, each set being fixedly spaced apart from each other.

12. The fluid delivery system of claim 1, wherein the workpiece is spaced a minimum distance from the second fluid outlet and/or the third fluid outlet.

13. A fluid transfer system according to claim 1, wherein the second and third fluid transporters have a diameter greater than the diameter of the first fluid transporter.

14. A fluid transfer system according to claim 1, wherein the distance between the first fluid transporter and the axis is greater than the distance between the second and/or third fluid transporter and the axis.

15. A fluid delivery system according to claim 1, wherein the pressure of the pressurised fluid at the second and/or third fluid outlets is greater than the external pressure of the fluid contained in the tank.

16. The fluid delivery system of claim 1, wherein the fluid is an electroplating solution.

17. A method of electroplating at least one workpiece comprising the steps of:

(a) delivering fluid from the first fluid outlet of the first fluid transporter into the tank,

(b) delivering pressurized fluid into the tank in oppositely facing directions from the second fluid outlet of the second fluid transporter and from the third fluid outlet of the third fluid transporter,

(c) moving the workpiece relative to the box along an axis between the second fluid outlet and the third fluid outlet,

(d) applying a first repelling force to the workpiece offset a first distance from the axis toward the second fluid transporter to move the workpiece toward the third fluid transporter, an

(e) Applying a second repelling force to the workpiece offset a second distance from the axis toward the second fluid transporter to move the workpiece toward the third fluid transporter,