WO2000061489A1

WO2000061489A1 - Method and apparatus for dispensing viscous material

Info

Publication number: WO2000061489A1
Application number: PCT/GB2000/001293
Authority: WO
Inventors: David Godfrey Williams
Original assignee: Crossflow International Limited
Priority date: 1999-04-08
Filing date: 2000-04-06
Publication date: 2000-10-19
Also published as: GB2352682A; AU3666000A; GB0008330D0

Abstract

A method of displacing solder paste or the like from a reservoir containing said paste or the like using pneumatic pressure wherein the paste or like is separated from the pneumatic pressure medium/air by means of an inflatable or expandable device or a contractible device such that the pressurised air or other gas does directly contact the solder paste, wherein a side or part of said device remote from the paste is pressurised such that the device is displaced so as to urge paste out of the reservoir.

Description

METHOD AND APPARATUS FOR DISPENSING VISCOUS MATERIAL

The present invention relates to a method and apparatus for displacing flowable materials and is especially intended for displacing solder paste from a paste supply cartridge to an applicator device used in applying solder paste through apertures in a stencil onto a substrate, such as a Printed Circuit Board (PCB), and such as disclosed in UK Patent Application GB 9903146.0 although can be used for applying other fluids such as viscous or other pastelike materials e.g. glue or adhesive.

Recent developments in the application of solder paste to metal stencils in the printing of PCB's have led to the utilisation of opaque plastics material cylindrical storage cartridges having a reduced diameter outlet passage securable to a paste applicator device and a larger, normally upper, open end to which a closure cap is hermetically securable with said cap having means for receiving a pneumatic line so as to enable the interior of the cartridge to be pneumatically pressurised so as to displace a plastic piston within the cartridge as desired to drive solder paste out of the cartridge via the outlet passage to the applicator device. Such cartridges are often of the type used for containing mastic or the like and have a hollow plastics piston therein normally drivable by a manually displaceable pressure rod displaceable by a one-way driving trigger mechanism. Because of the nature of the material and of the manufacturing tolerances involved in the production of such cartridges and pistons and because the cartridge cylinders are actually moulded with a slight taper (to permit withdrawal from the mould in the production process), there is a tendency for pressurised air to bleed past the piston and into the solder paste which has the disadvantage of initially driving out the liquid from between the solid solder paste balls. This leads to variations in the consistency of the solder paste with normally the first driven out contents having a greater fluid consistency than desired and then to a lesser fluid consistency than desired and also leads to the inclusion of air in the paste which is undesirable and results in the driven materials ceasing to be non-compressible. Additionally, there is a tendency for the plastics caplike piston to tilt or otherwise become jammed.

It is an object of the present invention to provide means for overcoming or minimising the abovementioned disadvantages.

According to the present invention there is provided a method of displacing solder paste or the like from a reservoir containing said paste or the like using pneumatic pressure wherein the paste or like is separated from the pneumatic pressure medium/air by means of an inflatable or expandable device or a contractible device such that the pressurised air or other gas does not directly contact the solder paste, wherein a side or part of said device remote from the paste is pressurised such that the device is displaced so as to urge paste out of the reservoir.

Initially there is described herein a method and device wherein the paste is displaced by a piston acted on by an expandable bellows device or a piston-like end of such a device as described in Application 9907948.5, although subsequently herein a preferred improvement is disclosed wherein the paste is contained within a compressible or contractible device, preferably bellows-like, within a pneumatically pressurised reservoir or reservoir housing.

According to a first aspect of the present invention there is provided a method of displacing solder paste from a reservoir containing said paste and having a slidably displaceable piston therein for acting on the solder paste, comprising applying pressure on said piston and pressure other than unrestrained or uncontained pneumatic pressure directly acting on said piston, to urge solder paste out of said reservoir. The pressure will preferably be applied by means of a pneumatically expandable or inflatable member which acts on said piston and thus since the air is contained within said member there is now little or no tendency of air to pass the piston and into the solder paste. By unrestrained or uncontained pneumatic pressure there is intended to be meant that the pressurised air is physically contained and prevented from acting at or on or in the region of the periphery of the piston so as to be physically prevented from being able to flow past the piston into the paste.

Also according to first aspect of the present invention there is provided improved reservoir means for solder paste or other paste-like or viscous material comprising a reservoir for containing said material and having an outlet therefor, displacing piston means slidable within said reservoir for displacing said material out of said outlet and means, other than unrestrained or uncontained pressurised air or liquid, for displacing said piston means within the reservoir to discharge paste or other material as desired.

Whilst said means for displacing said piston means will preferably include pressurised air or a defined or enclosed space for receiving the pressurised air, such space will be defined or delimited physically, e.g. by a bellows device such as a tubular bellows device, so as to prevent pressurised air from flowing past the piston and into the paste receiving or containing region.

Normally the reservoir will comprise a cylindrical housing or cartridge having a reduced diameter outlet passage at one end connectable to a solder paste applicator device and at the other end having means for enabling connection of said displacing means to the cartridge. Whilst the displacing means may comprise any mechanical means such as a displaceable piston or piston rod or other extendable or telescopic means acting on or including the paste or other material displacing piston, preferably said displacing means will comprise a pressurised air-receiving space within the cartridge enclosed or defined by an inflatable or expandable means such as a pneumatically extendable and retractable bellows sealing said space from the passage or possible passage between the cartridge wall and piston. The bellows may include the paste or other material displacing means at one end or, likely more normally, have a closed end abuttable against the displacing piston in the cartridge to drive such and the paste along the cylinder. Thus it will be appreciated that because pressurised air or liquid as the driving force is contained within the displacing means it cannot flow past the piston and into the paste or other material to cause the previously mentioned disadvantages.

Where the displacing means is an inflatable or extendable member such as a pneumatic bellows, such will be connected to an attachment device itself securable to the reservoir end to provide the counter support to permit the bellows to operate and venting means will preferably be provided in said attachment device, which will preferably be in the form of a cap, so as to ensure no overpressure or underpressure within the reservoir is created during operation.

Preferably the reservoir will be formed of plastics material and preferably such will be translucent or transparent so that the level of solder paste or other material within the cartridge can be readily inspected.

It is also intended that the present invention be applicable to existing solder paste dispensing cartridges insofar as such can be adapted by the provision of a displacing device according to the present invention so as to improve the operation. Thus, also according to the present invention there is provided a pneumatically/hydraulically displaceable bellows of a shape and dimension as to be insertable into a solder paste cartridge and having a closed end forming a paste displacing piston means or, preferably, having a closed end abuttable against an existing paste displacing piston and being connected at its other end to an end cap or closure cap having a through- passage for connection of the bellows to pressurised pneumatic/hydraulic source and said end cap being securable to said cylindrical cartridge - venting means also preferably being provided in said cap outwardly of the connection of the bellows with the cap or use a loose fit to enable the space between the bellows and the inside surface of the reservoir/cartridge to be vented.

More specifically according to the invention there is provided a solder paste or other viscous material reservoir means comprising an elongate tubular paste container having an outlet at one end and a closure cap at the other end, and having a paste-displacing-piston slidably displaceable therein under the action of pressurised air or fluid applied through an opening in said closure cap into a first space between said cap and said piston, characterised in that a tubular expandable or inflatable member for containing pressurised air/liquid extends between the opening in said cap and said displacing piston and hermetically or fluid tightly seals said first space from a remaining, second space between the inner surface of said tubular member and said second space preferably communicates with the surrounding, ambient atmosphere.

Whilst the present invention is primarily intended to be used in connection with solder paste, it may equally be applied for other purposes such as in the application of glue or other adhesives to overcome the hitherto disadvantages.

Also according to the invention, the use of a pneumatic bellows device as a driving means for a piston in a solder paste cartridge.

As mentioned earlier, according to a second and preferred aspect of the invention a method of displacing solder paste from a collapsible/contractible inner reservoir containing said paste contained within an outer reservoir or container comprises pressurising the surrounding space within the outer reservoir so as to cause the inner reservoir to collapse or contract and paste to be discharged therefrom. Thus according to a second and preferred aspect of the invention there is provided improved reservoir means for solder paste or other paste-like or viscous material, comprising a first, outer pneumatically pressurisable reservoir or container having a second, inner collapsible or contractible container or reservoir therein with an outlet communicating with the exterior, with said second and inner reservoir being reduceable in extension or other dimension under pneumatic pressure to discharge paste or the like therefrom.

Preferably, the outer reservoir is a tube having an inlet for pressurised air and containing the inner reservoir in the form of a collapsible bellows sealed at one end against the tube with an outlet extending externally and being connectable to a paste receiving machine or device not forming part of the invention. By forming the bellows of circular cross section with concertinalike sides and such as not to collapse inwardly towards its longitudinal axis, the inner reservoir is urged, when the space between it and the inner walls of the outer reservoir is pressurised, to discharge paste. This arrangement avoids the discovered possible disadvantage of any paste displacing piston jamming at the outlet end of a paste tube reservoir.

A deficiency which has led to the development of a third aspect of the invention has been the discovery that in some solder paste printing machines for applying paste via a stencil onto a substrate therebeneath and operating at high speed, and where solder paste is displaced from the reservoir by the application of pneumatic pressure to bellows in the reservoir acting as a piston during the paste application stroke and then such pressure is relieved upon commencement of the next paste application stroke of the machine, it has been found there is insufficient time, especially with high speed machines operating such as with an application stroke of one second, for the bellows to be sufficiently re-pressurised to urge more paste from the reservoir within the short time available. This is increasingly the case as paste is discharged since the bellows expand from the top of the reservoir downwardly and thus a greater volume of air is required to re-pressurize such and hence there is a slight time delay before such becomes effective.

A possible partial remedy for the delay in operation as hitherto a paste displacing means expanded in volume, would be to gradually increase the pneumatic pressure or to enlarge the diameter of the supply pipes etc., to increase the pneumatic supply which is a more complex and expensive proposal and the present invention provides a solution without having to adapt the attachment supply pipes etc.

According to a third aspect of the present invention there is provided a device for maintaining the speed of discharge of paste-like or other viscous material from a reservoir as said material is discharged, comprises a pressing means for exerting pressure on the material in the reservoir, displaceable supporting means for supporting said pressing means, and means for ensuring said supporting means is displaceable in a non-return manner in its operative condition, (and preferably biasing means acting in the direction of movement of the supporting means), and energisable drive means or means for receiving a pressurised fluid (such as air or hydraulic oil) acting as drive means, for the intermittent displacement of said supporting means in the operating cycle of a solder paste or other material printing machine.

Preferably the pressing means comprises a pneumatically or hydraulically expandable, inflatable or otherwise enlargeable member which in operation does not increase in its volumetric capacity for pressurised fluid and whilst it might be mounted externally of the reservoir, it is preferably mounted within the reservoir. Preferably, the pressing means has a portion or part in direct contact with the fluid material surface or a piston/pressing member in contact with said surface of the material and preferably the pressing means is supported at the end of a tube sliceable mounted to be displaceable within the reservoir, said tube also acting as a supply duct for the pressurising fluid for operating the pressing means and said tube being biased to move into the reservoir by any suitable means, such as a compression spring acting between a cap for the reservoir and the pressing means covered by the tube, or as a gravity bias or by means of a separate pneumatic or other pressurisation of the space on the side of the pressing means remote from the material.

Thus it will be appreciated that the device according to the present invention may be used to adapt existing paste cartridges and is not necessarily related to the subject of GB 9907948.5

Also according to the third aspect of the present invention there is provided improved reservoir means for solder paste or other paste-like or viscous material comprising a reservoir for containing said material and having an outlet therefor, material-displacing piston means slideable within said reservoir for displacing said material out of said outlet, and displacement means for receiving pressurised medium (such as pressurised air or liquid) for enabling displacement of said piston means within the reservoir to discharge the paste or other material, characterised by the feature that the displacement means for displacing said piston means is such as to have minimal or little expansion or inflation or other enlargement and is displaceable within said reservoir means to act on and follow the surface of material remote from the outlet as said material is discharged, and means for ensuring said displacement means moves in only one direction during paste displacement operation.

The concept behind this third aspect of the present invention is to maintain the expandable, inflatable or otherwise enlargeable means which receives the pressurised medium at a generally constant and preferably minimal volume rather than of continually increasing the volume thereof as occurs with a long and gradually increasing expandable bellows device with paste-displacing piston at one end and being fixed the other end. In the present invention, by constantly moving the displacing means in a single direction so as to follow the paste level remote from the outlet as the paste is discharged, the volume of air for example in the displacing means remains constant and minimal and thus said means has constant speed of operation and thus there is no requirement to, otherwise continually increase the pressure during operation to compensate for enlargement which might be done either manually or by a more complex arrangement.

It will be appreciated that with the displacing means being constant volume for each enlargement and being carried on the end of a displaceable supporting tube, which is preferably slideably mountable in a cap or other closure for the reservoir, and that as it together with the displacing means, moves into the reservoir, is no change in the volume of the air in the circuit causing displacement of the piston and thus there is no time lag in operation nor need to increase the pressure with the consequential operation steps.

Preferably, the tube will have a releasable one-way movement control device, such as a ratchet or an angled locking plate with spring bias such as of the type such as used in mastic guns which allow a solid displacement rod to be progressively driven by manual operation of a trigger into a mastic container and prevented from withdrawal until the locking plate is manually released. Any suitable form of one way displacement control mechanism may be used. To ensure the tubular piston rod moves with each operation, a spring means may be located exteriorly of the tube and therearound and within the reservoir between the displacement means and a cover for the reservoir to bias the displacing means in the direction of the fluid material. Instead of the spring means, pneumatic air pressure may be provided from a separate pressurised source to create a similar bias.

In an alternative arrangement of this third aspect, a displacement means for displacing piston unit is totally pneumatically operable with the said built-in one-way control being by means of an expandable member such as a rubber ring carried by a main body and which ring is pressurised into retaining engagement with the walls of the reservoir to hold the device in position, whereupon another displacement piston in engagement with the paste displacing piston means of the reservoir, is displaced by pneumatic pressure which, when relieved, enables the main body of the device to follow it to move further into the reservoir since at the same time the expandable ring means in engagement at the side walls is relieved to enable forward movement of the ring, pressurising means and main body, and the operation is then repeated.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: -

Fig. 1 is a vertical section through an apparatus according to the first aspect of the invention installed in a solder paste-dispensing cartridge;

Fig. 2 is an enlarged section of the pneumatic bellows device of Fig. 1 shown alone and in the expanded condition;

Fig. 3 is an elevational view of the bellows of Fig. 2;

Fig. 4 is a vertical schematic section through an embodiment forming a second aspect of the invention;

Fig. 5 is a schematic illustration of an embodiment forming a third aspect of the invention by way of a partial cross section through a reservoir;

Fig. 6 is a plan of a stabilising ring which is to be inserted in the regions of the concertina part of the bellows and therearound so as to maintain the stability and alignment thereof and has projections for centering such; and

Fig. 7 is a schematic section through an alternative embodiment of displacing device of this third aspect wherein in a similar manner to that of Fig. 5, a support tube is displaceably mounted in a cover for the reservoir but instead of the one way control device as illustrated in Fig. 5 by way of a rocking tilting lever, this device has a rubber ring which is expandable and contractible during operation to grip and release the sides of the reservoir.

In Fig. 1 there is illustrated a reservoir means in the form of an elongate plastics material cartridge comprising a housing 1 of circular cross- section having a reduced diameter outlet portion 2 at its normally lower end securable by threaded means (not shown) to a solder paste applicator device (also not shown). At the upper end of housing 1 a peripheral flange 3 is formed to which a closure cap 4 is detachably connectable in known manner and said cap 4 has a central aperture 5 through which there extends a pneumatic connection part 6 of a pneumatically expandable/extendable plastics material bellows device 7. Bellows device 7 is a tubular or concertina-like construction of circular cross-section and has a closed end 8 which rests inside the sealing walls 9' of a cap-like plastics piston 9 slideably and sealingly engagable along the inside surface 10 of housing 1 so as to drive solder paste when positioned in space 11 outwardly via outlet 2.

The bellows device 7 is shown in Fig. 1 in its collapsed or unextended condition although when pressurised air is provided from a pneumatic source via connection part 6 it is expandable to drive the piston 9, as desired, along the cylinder surface 10. A venting aperture (not shown) is provided in cap 4 so as to prevent the space 12 between the outer surface of bellows 7 and the inner surface 10 of housing 1 being subject to any undesirable under pressure or over pressure.

It will be appreciated that the end closure 8 of the bellows 7 is of a diameter such as to rest on the outer parts or walls 9' of the piston 9 and to act to enhance the sealing action of said piston. The bottom wall 8' of end closure 8 is downwardly convex to match the contours of the abutting surface of plastics piston 9.

The material from which the housing 1 is made is normally plastics material and preferably such is translucent or transparent so that the contents in space 11 can be readily viewed.

Mechanical means for displacing the paste driving piston may be provided instead of pneumatic bellows 7 and also drive means therefor provided and operable via the controls of a screen printing machine. However, if to be used to adapt existing solder paste cartridges, the mechanical means and drive therefor will have to be dimensioned and constructed to fit within the constraints of the space available in the screen printing machine.

An alternative and preferred embodiment of the invention is schematically illustrated in Fig. 4, wherein the solder paste is to be contained within an inner reservoir device 12 formed as a cartridge-like collapsible bellows device which is closed at its normally upper end and has an externally threaded outlet neck 14 extending from the end wall 15 at the other end for connection to a paste applicator device (not shown).

The inner reservoir device 12 is located mainly within an outer tubular reservoir or container 16 which has an aperture 17 at its lower end for the extension of neck 14 and the lower face of end 15 is air-tightly bonded or sealed to the end face 18 of container 16. The other end 19 of tubular container 16 has an inlet aperture 20 for the connection for the connection of the duct of a pneumatic power source (not shown).

The pleats/concertina portion of the reservoir 12 are constructed and of such material so as to resist inward collapse towards the longitudinal central axis of the container 12, such that on pressurisation of the space between the reservoir 12 and container 16, the end 13 moves towards outlet 14 thereby discharging paste from the reservoir 12 until almost all is expelled. At least in the outer peripheral region to end plate 13, an annular space is formed to receive the pleats on collapse of the reservoir 12 to ensure as much as possible paste is discharged.

It is envisaged that reservoir 12 may be rechargeable with paste e.g. via air valved inlet (not shown) in the region of arrow B. In Fig. 5 there is illustrated a tubular reservoir 21 of circular cross section and of plastics material and having an outlet 22 at its lower end and a wider upper end 23 for receiving a closure cap 24 having a central aperture 25 through which a slideable support tube 26 slideably extends and which tube 25 is connectable at its upper end to a pneumatic air supply tube (not shown) connected to a pneumatic source and a control of a solder paste printing machine (not shown). Tube 26 at its lower end 28 carries a short bellows device 29 and is in pneumatic communication therewith. The device 29 is of tubular and of circular cross section and paste displacing piston 30 closes the lower end of the bellows and sealingly slides along the walls of reservoir. The bellows 29 is expandable by air entering intermittently through said tube 26 in synchronisation with the operation of the solder paste printing machine (not shown) to which the device is attached.

A compression spring 31 is provided extending between a lower interior face 32 of the closure cap 24 and the upper surface 29' of the connection of the bellows device 29 to the tube 26 and operates such as to bias the bellows and piston and the tube downwardly as the level of paste in the reservoir 32 drops during operation. A one-way movement control device 33 in the form of a tilting locking plate 34 which is spring biased upwardly from below (not shown) into the locking position and held at one edge 34 by a lip 24' of cap 24. The one-way control device 33 is similar to and operates in the manner of one way devices used in mastic cartridge displacement guns but here the tube 26 displacing pressure is provided by the pneumatic pressure and the spring 31 rather than a separate manually operable trigger.

It is to be observed that the bellows device 29 is of a short length and a length which will not discharge the whole of the reservoir and is much shorter than hitherto envisaged so as to minimise the volume of air necessary to effect the necessary amount of paste displacement. Also, since the bellows device 29 at the lower end of tube 26 moves into the reservoir 21 there is no need for it to continuously increase in volume as the paste is discharged, nor is such possible, but rather it has a constant and rapid operation.

It is envisaged that to maintain contact with the paste, instead of the biasing spring 31 within the reservoir (or possibly outwardly and above cap 24), if the piston or bellows seals against the insides of the reservoir the space above such may be pressurised from a separate pneumatic supply (not shown) so as to maintain a bias thereon. Alternatively, even a mass and gravity effect may achieve the necessary result.

Thus, in use, as the bellows device 29 is alternatively pressurised and depressurised, the whole of the bellows device 29 with piston 30 moves in stepwise manner together with tube 26, downwardly along the reservoir 21 so as to discharge paste through outlet 22 in synchronisation with the machine it is being used with (not shown).

A C-shaped stabilisation ring 35 is illustrated in Fig. 2 which may clip around the outside of bellows 29 and has projections 36 which centralise the ring and bellows so as to ensure a proper and aligned displacement. Alternatively, the bellows pleats may be moulded to have integral centralising projections.

In the alternative embodiment illustrated in Fig. 3, the device 27 comprises a lower main body 28 having two rubber 0-ring seals 29 in grooves and over which an inverted dome-like piston 40 is slideable in sealing relationship. Piston 40 may carry exteriorly thereof a plastics, for example, paste-displacing piston or cap (not shown) slideably displaceable against the inner walls of the reservoir 21 in closing fitting relationship. Alternatively as shown, the dome-like piston 40 has upper sealing lips which slideably and sealingly slide on the walls of reservoir and the lower face acts directly on the solder paste beneath (not shown). A slideable tube 43 with piston 44 is located in a bore 45 of the device and is biased upwardly by spring 46 and acts at its lower end against piston 40 to urge such downwardly. Bore 45 is connectable to a pneumatic source which acts on piston 44 to displace such downwardly to discharge paste. A throttle (not shown) delays displacement of piston 44 until an upper chamber 46 of a one-way control device is pressurised via opening 48 in tube 45 leading to ducts 49 and clutch 46. An end wall or plate 50 is fixedly mounted on tube 45 and upwardly limits chamber 46. A sealing 0-ring 51 is provided. Outwardly of plate 50 is a cup-like piston 52 sliding over seal 51 and over a seal 53 in a groove of a mounting member 54 carried by the tube 55 and has curved portions 52' which act on a larger 0-ring 55 supported from below by curved portions 21" of main body 28. Ring 55 is compressible by the downward movement of piston 52 so as to deform into gripping engagement with the inside walls of reservoir 21 whereupon the piston 40 then (because of the delay of the throttling means) moves downwardly to displace paste. Upon depressurisation, the 0-ring 55 disengages from reservoir 21 and under the action of spring 46 and gravity moves downwardly so that main body 28 moves back into piston 40 - the frictional seal of piston 40 with reservoir 21 enabling this action. Plate 50 and piston 52 follow and the operation is repeated to cause a step-wise progression of the device down the reservoir 21.

Claims

1. A method of displacing solder paste or the like from a reservoir containing said paste or the like using pneumatic pressure wherein the paste or like is separated from the pneumatic pressure medium/air by means of an inflatable or expandable device or a contractible device such that the pressurised air or other gas does not directly contact the solder paste, wherein a side or part of said device remote from the paste is pressurised such that the device is displaced so as to urge paste out of the reservoir.

2. A method as claimed in claim 1 , in which the paste is displaced by a piston acted on by an expandable bellows device or a piston-like end of such a device.

3. A method as claimed in claim 1 , in which the paste is contained within a compressible or contractible device, preferably bellows-like, within a pneumatically pressurisable reservoir or reservoir housing and displaced thereout of by applying pneumatic pressure.

4. A method of displacing solder paste from a reservoir containing said paste and having a slideably displaceable piston therein for acting on the solder paste, comprises applying pressure on said piston and pressure other than unrestrained or uncontained pneumatic pressure, as herein defined, directly acting on said piston to urge solder paste out of said reservoir.

5. A method as claimed in claim 4, in which the pressure is applied by means of a pneumatically expandable or inflatable member which acts on said piston and such that since the air is contained within said member there is little or no tendency for air to pass the piston and enter the solder paste.

6. Reservoir means for solder paste or other paste-like or viscous material comprises a reservoir for containing said material and having an outlet therefor, displacing piston means slideable within said reservoir for displacing said material out of said outlet and means, other than unrestrained or uncontained pressurised air or liquid, for displacing said piston means within the reservoir to discharge paste or other material as desired.

7. Reservoir means as claimed in claim 6, in which said means for displacing said piston means includes pressurised air or a defined or enclosed space for receiving the pressurised air and said space is defined or delimited physically so as to prevent pressurised air from flowing past the piston and into the paste receiving or containing region.

8. Reservoir means as claimed in claim 7, in which said space is defined by a bellows device such as a tubular bellows device.

9. Reservoir means as claimed in any of claims 6 to 8 which comprises a cylindrical housing or cartridge having a reduced diameter outlet passage at one end connectable to a solder paste applicator device and, at the other end, having means for enabling connection of said displacing means to the cartridge.

10. Reservoir means as claimed in any of claims 6 to 9, in which the displacing means comprises any mechanical means, such as a displaceable piston or piston rod or other extendable or telescopic means, acting on or including the paste - or other material - displacing piston or said displacing means comprises a pressurised air-receiving space within the cartridge enclosed or defined by an inflatable or expandable means, such as a pneumatically extendable and retractable bellows sealing said space from the passage or possible passage between the cartridge wall and piston.

11. Reservoir means as claimed in at least claim 8, in which the bellows include the paste or other material displacing means at one end or have a closed end abuttable against the displacing piston in the cartridge to drive such and the paste along the cylinder.

12. Reservoir means as claimed in any of claims 6 to 11 , in which the displacing means for displacing the piston is an inflatable or extendable member, such as a pneumatic bellows, and is connected to an attachment device itself securable to the reservoir end to provide the counter support to permit the bellows to operate.

13. Reservoir means as claimed in claim 12 in which venting means are provided in said attachment device, so as to ensure no overpressure or underpressure within the reservoir is created during operation.

14. Reservoir means as claimed in claim 13, in which the attachment device is a cap.

15. Reservoir means as claimed in any of claims 6 to 14, in which the reservoir is of translucent or transparent material so that the level of solder paste or other material within the cartridge can be readily inspected

16. A pneumatically/hydraulically displaceable bellows of a shape and dimension as to be insertable into a solder paste cartridge and having a closed end forming a paste displacing piston means or, preferably, having a closed end abuttable against an existing paste displacing piston and being connected at its other end to an end cap or closure cap having a through- passage for connection of the bellows to pressurised pneumatic/hydraulic source and said end cap being securable to said cylindrical cartridge.

17. A bellows as claimed in claim 16, including venting means provided in said cap outwardly of the connection of the bellows with the cap or is a loose fit of the cap to enable the space between the bellows and the inside surface of the reservoir/cartridge to be vented.

18. A solder paste or other viscous material reservoir means comprising an elongate tubular paste container having an outlet at one end and a closure cap at the other end, and having a paste-displacing-piston slideably displaceable therein under the action of pressurised air or fluid applied through an opening in said closure cap into a first space between said cap and said piston, characterised in that a tubular expandable or inflatable member for containing pressurised air/liquid extends between the opening in said cap and said displacing piston and hermetically or fluid tightly seals said first space from a remaining, second space between the inner surface of said tubular member and said second space preferably communicates with the surrounding, ambient atmosphere.

19. The use of a pneumatic bellows device as a driving means for a piston in a solder paste cartridge.

20. A method of displacing solder paste from a collapsible/contractible inner reservoir containing said paste contained within an outer reservoir or container comprises pressurising the surrounding space within the outer reservoir so as to cause the inner reservoir to collapse or contract and paste to be discharged therefrom.

21. Reservoir means for solder paste or other paste-like or viscous material, comprising a first, outer pneumatically pressurisable reservoir or container having a second, inner collapsible or contractible container or reservoir therein within an outlet communicating with the exterior, with said said second and inner reservoir being reduceable in extension or other dimension under pneumatic pressure to discharge paste or the like therefrom.

22. Reservoir means as claimed in claim 21 , in which the outer reservoir is a tube having an inlet for pressurised air and containing the inner reservoir in the form of a collapsible bellows sealed at one end against the tube with an outlet extending externally and being connectable to a paste receiving machine or device not forming part of the invention.

23. Reservoir means as claimed in any of claims 6 to 22, in which displaceable supporting means are provided and support said means for displacing said piston means, and said supporting means are mounted so as to be displaceable in non-return manner in its operative condition.

24. A device for maintaining the speed of discharge of paste-like or other viscous material from a reservoir as said material is discharged, comprises a pressing means for exerting pressure on the material in the reservoir, displaceable supporting means for supporting said pressing means, and means for ensuring said supporting means is displaceable in a non-return manner in its operative condition, and energisable drive means or means for receiving a pressurised fluid (such as air or hydraulic oil) acting as drive means, for the intermittent displacement of said supporting means in the operating cycle of a solder paste or other material printing machine.

25. A device as claimed in claim 24, in which the non-return means includes biasing means acting in the direction of movement of the supporting means.

26. A device as claimed in claim 24 or 25, in which the pressing means comprises a pneumatically or hydraulically expandable, inflatable or otherwise enlargeable member which in operation does not increase in its volumetric capacity for pressurised fluid.

27. A device as claimed in claim 26, in which the pressing means is mounted within the reservoir.

28. A device as claimed in claim 26 or 27, in which the pressing means has a portion or part in direct contact with the fluid material surface or a piston/pressing member in contact with said surface of the material.

29. A device as claimed in claim 28, in which the pressing means is supported at the end of a tube slideably mounted to be displaceable within the reservoir, said tube also acting as a supply duct for the pressurising fluid for operating the pressing means and said tube being biased to move into the reservoir by any suitable means, such as compression spring acting between a cap for the reservoir and the pressing means covered by the tube, or as a gravity bias or by means of a separate pneumatic or other pressurisation of the space on the side of the pressing means remote from the material.

30. Reservoir means for solder paste or other paste-like or viscous material comprising a reservoir for containing said material and having an outlet therefor, material-displacing piston means slideable within said reservoir for displacing said material out of said outlet, and displacement means for receiving pressurised medium (such as pressurised air or liquid) for enabling displacement of said piston means within the reservoir to discharge the paste or other material, characterised by the feature that the displacement means for displacing said piston means is such as to have minimal or little expansion or inflation or other enlargement and is displaceable within said reservoir means to act on and follow the surface of material remote from the outlet as said material is discharged, and means for ensuring said displacement means moves in only one direction during paste displacement operation.

31. Reservoir means as claimed in claim 30, in which with the displacing means being constant volume for each enlargement and with such being carried on the end of a displaceable supporting tube and such that as it moves into the reservoir, there is no change in the volume of the air in the circuit causing displacement of the piston and thus there is no significant time lag in operation nor need to increase the pressure with the consequential operation steps.

32. Reservoir means as claimed in claim 31 , in which the supporting tube is slideably mountable in a cap or other closure for the reservoir.

33. Reservoir means as claimed in claim 31 , in which the supporting tube and displacing means are displaceable into the reservoir.

34. Reservoir means as claimed in at least claim 30, in which the tube has a releasable one-way movement control device.

35. Reservoir means as claimed in claim 34, in which the one-way device is a ratchet or an angled locking plate with spring bias.

36. Reservoir means as claimed in at least claim 31 , in which to ensure the supporting tube moves with each operation a spring means is located exteriorly of the tube and therearound and within the reservoir between the displacement means and a cover for the reservoir to bias the displacing means in the direction of the fluid material.

37. Reservoir means as claimed in claim 36, in which instead of the spring means, pneumatic air pressure are provided from a separate pressurised source to create a similar bias.

38. Reservoir means as claimed in any of claims 30 to 37, in which a displacement means for displacing piston unit is totally pneumatically operable with the said built-in one-way control being by means of an expandable member such as a rubber ring carried by a main body and which ring is pressurised into retaining engagement with the walls of the reservoir to hold the device in position, whereupon another displacement piston in engagement with the paste displacement piston means of the reservoir, is displaced by pneumatic pressure which, when relieved, enables the main body of the device to follow it to move further into the reservoir since at the same time the expandable ring means in engagement at the side walls is relieved to enable forward movement of the ring, pressurising means and main body, and the operation is then repeated.

39. A reservoir means/device substantially as herein described with reference to Figs. 1 to 3, Fig. 4, Figs. 5 and 6 or Fig. 7 of the accompanying drawings.