GB2213745A - Apparatus for assembling circuit components - Google Patents

Abstract

The apparatus has a pick-up tool 6 supported at one end of a horizontally extending support arm 12. The support arm is mounted for horizontal sliding movement relative to a cup-shaped support member 14 eccentrically mounted relative to a rotatable boss 20. The boss is journalled for rotation about a fixed vertical support spindle 24. Reciprocation of the arm 12 and rotation of the cup-shaped support member 14 enables the pick-up tool 6 to be moved along a linear path for positioning components on a printed circuit board. The pick-up-tool 6 is connected to a vacuum source so that its nozzle 8 can pick up a circuit component from a turnable 36. The tool is then moved to position the component relative to the circuit board and the vacuum released to deposit the component on the circuit board. <IMAGE>

Description

APPARATUS FOR ASSEMBLING CIRCUIT COMPONENTS.

The present invention relates to apparatus for assembling circuit components.

The size of the circuit components to be affixed onto printed circuit boards is now so reduced that it is not possible for operators to position the components by hand on a board prior to soldering.

Accordingly, equipment is provided to assist operators to pick-up individual circuit components and to position them as required on a printed circuit board.

This known equipment generally includes a pick-up tool which is used to pick-up an individual component by applying vacuum thereto. The component is positioned whilst still held on the tool by the vacuum, and then the vacuum, and hence the component, is released.

It is known to provide simply a hand held and hand operated vacuum pick-up tool. However, as it is generally important for the tool to be accurately orientated before a component is deposited, hand held tools are not totally satisfactory. Therefore, equipment has been developed in which a vacuum pick-up tool is fixedly mounted at the correct orientation.

Of course, in this case, means have to be provided to enable movement of the tool between at least one supply of circuit components and a holder for a printed circuit board.

It is known to enable movement of the pick-up tool by mounting it on a support slidable with respect to two mutually orthogonal guides. However, this requires the operator to move the tool between any two points using a triangulation technique which is very unnatural.

It has been proposed to mount the pick-up tool on the end of a manipulator arm having a number of pivoted sections. Although this enables the operator to move the tool in a more natural manner, this arrangement cannot reliably ensure that the pick-up tool remains accurately at the correct orientation.

The present invention seeks to reduce the disadvantages of known equipment.

According to a first aspect of the present invention there is provided mounting apparatus for a working tool comprising first and second support members, and holding means on one of said support members for holding a working tool, wherein said first support member is rotatable about a first axis and said second support member is linearly reciprocable in a plane substantially at right angles to said first axis, and wherein said first and second support members are interconnected such that said holding means can be subjected to a combination of their movements whereby said holding means can be moved between two points along a substantially linear path.

Preferably, the first and second support members are arranged such that the holding means is movable along a substantially linear path between any two points in an annular working plane which extends substantially parallel to said plane in which said second support member is movable.

In an embodiment, the mounting apparatus defined above is included in apparatus for assembling circuit components. Thus, the working tool to be held by the holding means may be a vacuum pick-up tool selectively connectable to a vacuum source. It will be appreciated that the vacuum pick-up tool can be held by the holding means in a predetermined and fixed orientation and that the operator can move the tool substantially anywhere in its working plane along a straight line. The apparatus is therefore simpler for an operator to use than those previously available.

The vacuum pick-up tool is preferably removably supported by said holding means. In this respect, other tools can interchangeably be received by the holding means. Usually, it is required to apply an adhesive or solder in a pasty form to the circuit board before the circuit components are positioned thereon, and this can be done by an applicator tool removably held by said holding means.

Preferably, said second support member is an elongate arm slidably received in guide means of said first support member. In an embodiment, said guide means comprise a plurality of wheel bearings arranged to define a guide path for said support arm.

In a preferred embodiment said wheel bearings are rotatably fixed to the inner surface of the base of a cup-shaped member forming said first support member.

Appropriate slots or holes are provided in the upstanding peripheral walls of said cup-shaped member and aligned with said guide path through which said support arm extends. Said cup-shaped support member is journalled with respect to a support spindle.

In an embodiment, the support arm is arranged to extend substantially horizontally, and said first support member is rotatable about a substantially vertically extending support spindle. Preferably, a turntable is additionally arranged below said arm for rotation about said support spindle. The holding means for said working tool is provided at one end of said arm.

In a preferred embodiment said cup-shaped support member is eccentrically mounted relative to said support spindle.

Preferably, a passage extends through said spindle, through said cup-shaped support member and through said arm to facilitate the connection of said holding means to a vacuum.

According to a further aspect of the present invention there is provided a vacuum tool comprising means defining a vacuum path communicating with an outlet, means enabling reciprocable movement of the outlet along a longitudinal axis, means enabling the outlet to pivot about said longitudinal axis, and manually operable valve means carried by said tool for controlling the application of vacuum to said outlet Preferably, said means enabling the outlet to pivot about said axis, enable the outlet to rotate about said axis.

In a preferred embodiment, said vacuum path defining means comprises a pipe extending along said longitudinal axis, a first end of said pipe defining said outlet, and a second end thereof being selectively communicated with atmosphere by way of said valve means. A nozzle may be removably carried by said pipe in communication with said outlet.

A vacuum tool as defined above can be releasably mounted in holding means of the mounting apparatus and of the assembling apparatus also defined above. In this respect, the vacuum tool is mounted such that its longitudinal axis extends substantially vertically, and so that, when'the vacuum tool is held on one end of the horiz'ontally extending support arm, the nozzle can be moved up and down to enable it to pick-up a component, and subsequently to deposit that component.

It is also advantageous for the nozzle to be pivotable, preferably rotatable, so that the component can be correctly oriented prior to its deposit.

The vacuum tool according to the further aspect of the invention also has manually operable valve means carried by the tool. This enables an operator easily, and with one hand, to pick-up, position, and deposit a component. Presently, there are no known examples of vacuum tools which enable one handed operation when supported on an assembling apparatus.

Along its length, between its first and second ends, the pipe defining the vacuum path of the tool is preferably provided with a bore for communicating the interior of the pipe with a vacuum source.

In an embodiment, the vacuum pipe extends substantially coaxially through a rigid pipe forming a tool body. The vacuum pipe is journalled within this tool body for rotation with respect thereto.

Furthermore, said vacuum pipe is fixed to a sleeve member slidable with respect to said tool body. Said manually operable valve means are preferably housed by said sleeve member and are operable by way of a push-button resiliently mounted on said sleeve member.

The present invention extends to holding means for a circuit board comprising two elongate support members, and means for releasably maintaining said elongate members in substantially parallel relationship at a predetermined spacing, and further comprising resilient means for enabling movement of one of said elongate members relative to the other and for causing said one elongate member to be returned to a position in which said predetermined spacing is maintained.

The holding means defined above may be incorporated in mounting apparatus or in assembling apparatus as also defined above.

Preferably, the two elongate support members of the holding means are two shaped bars connected together in spaced parallel relationship by two or more tie rods. The length of these rods is adjustable, for example, by forming them from telescopic sections or the like. In an embodiment, a selected one of the bars is attached to each of the tie rods by the resilient means which resiliently bias said one bar towards the other bar. Thus, the one bar is movable, against the force of the resilient means, away from the other bar as required, but on release, is reliably positioned again by the resilient means at the predetermined spacing from the other bar.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a perspective view of an embodiment of apparatus of the invention for assembling circuit components, Figure 2 shows a further perspective view of the apparatus of Figure 1 showing arm rests, a dust cover partially removed, and the arm in a different position, Figure 3 shows a section taken along the line A-A of Figure 1, Figure 4 shows a perspective view of a vacuum pick-up tool, Figure 5 shows a vertical section through the tool of Figure 4, and, Figure 6 chows a further perspective view of apparatus as shown in Figures 1 and 2 with additional components.

The apparatus illustrated in Figures 1, 2 and 6 is for use in the positioning of circuit components on printed circuit boards. In this respect, the apparatus is provided with holding means 2 in which a circuit board 4 (Figure 6) can be supported. A vacuum pick-up tool 6 is carried by the apparatus and is connected with a vacuum source (not shown) so that if its nozzle 8 is positioned in contact with, or near a circuit component, this circuit component will be held against the nozzle 8. Accordingly, an operator can move the tool 6 to pick-up a required circuit component, move the component to the circuit board 4, and then position that component relative to the circuit board 4. The vacuum is then released, by operation of a push-button 10 of the tool 6, to deposit the circuit component on the printed circuit board 4 in the correct position.

It is known to fabricate printed circuit boards using a vacuum pick-up tool for positioning the circuit components, and accordingly, this method of fabrication will not be further described.

The novel apparatus illustrated in Figures 1, 2 and 6 is particularly simple for an operator to use and enables components to be reliably, accurately positioned. In this respect, the operator is able to move the tool 6 substantially in a straight line between any two positions in its working plane, and this considerably facilitates use of the apparatus.

It will be seen that the pick-up tool 6 is supported, with its longitudinal axis extending substantially vertically, at one end of an elongate support arm 12.

The support arm 12 is mounted for horizontal, sliding movement relative to a support member 14. As is shown in Figure 3, the support member 14 is a substantially cylindrical cup-shaped member having a removable planar top cover 15 formed in two substantially semi-circular halves. The arm 12 extends across a diameter of the cup-shaped member 14. Three wheel bearings journalled for rotation about respective vertical spindles are mounted within said cup-shaped member 14 on its base. These three wheel bearings, which are not visible in the drawings, are arranged to define a guide path for the arm 12 with two bearings on one side of the path and the other bearing on the opposite side thereof. In the embodiment illustrated the arm 12 has an accurately square cross-section but is mounted turned through 45 degrees such that two opposed corners of the arm 12 contact the wheel bearings.Each wheel bearing has a corresponding grooved cross-section for receipt of a respective corner of the arm 12. The wheel bearings are constructed as precision bearings. Furthermore, the vertically extending spindle of at least one of the wheel bearings is horizontally adjustable so so that the bearings can be adjusted to form an accurate guide path extending diametrically of the cup-shaped member 14 along which the arm 12 can be reciprocated. The cylindrical upstanding peripheral wall of the cup-shaped member 14 is slotted, as indicated at 16, at two diametrically opposed positions aligned with said guide path to further receive and guide the arm 12. At each end the arm 12 is provided with a respective screw 18 forming a stop member for engagement with the peripheral wall of the cup-shaped support member 14 to limit the reciprocating movement of the arm 12.

As can be clearly seen in Figure 3, the cup-shaped support member 14 is eccentrically mounted relative to a rotatable boss 20. In fact, in the embodiment illustrated the cup member 14 and the boss 20 are integrally formed. The boss 20 is journalled by bearings 22 for rotation about a fixed support spindle 24. In this respect, in the embodiment illustrated, the support member 14 is fixed to and supported by a rotatable cylindrical sleeve 26 which is concentric with, and rotatable relative to, the fixed support spindle 24. The support spindle 24 is held captive on a base plate 28 by way of a nut 30. A base cover member 32 is connected to the base' plate 28 and supported at its internal edge by part of the fixed spindle assembly 24.

A flanged rotatable sleeve bearing 34 is mounted for rotation about said spindle 24 and relative to said base cover 32. A circular turntable 36 is supported on and fixed, for example by a screw 38, to said rotatable sleeve bearing 34 such that the turntable is rotatable relative to the spindle 24. As illustrated, the turntable 36 is provided with an annular recess 39 in which circuit components may be received either individually or in pots 40 therefor as shown in Figure 6. It will be seen that the cylindrical sleeve 26 and hence the cup-shaped member 14 are supported by the sleeve bearing 34 and its turntable 36. However, rotation of the turntable 36 relative to the sleeve 26 is possible. The sleeve 26 is provided with a circumferential groove 42 around its periphery in which a plastics material cover 44 is supported. This cover 44, which as shown in Figure 2 is constructed in two semi-circular halves, is fixed to the cylindrical sleeve 26 to extend substantially horizontally and is preferably fixed in place by a screw 45. The cover 44 acts as a dust cover for the contents of the annular recess 39 within the turntable 36. A radially extending groove 47 is formed in the cover 44 and is arranged substantially in alignment with the arm 12. It will be appreciated that the arm 12 and the groove 47 will always be in alignment as they rotate relative to the turntable 36. Thus, the groove 47 allows acces to the contents of the recess 39 of the turntable to the tool 6.

It will be appreciated that the arm 12 can be reciprocated in the horizontal plane guided by the wheel bearings and by the slots 16 in the cup-shaped member 14 independently of the rotational position of this cup-shaped member 14. Similarly, the cup-shaped member 14 is freely rotatable about the spindle 24 irrespective of the position of the arm 12.

The stop members 18 define inner and outer limits for the sliding movement of the arm 12 and thus, an annular, horizontally disposed, working plane within which the tool 6 can be positioned by relative movements of the arm 12 and of the cup-shaped member 14 is defined. It will also be appreciated that the tool 6 can be moved between any two positions within this annulus in a substantially straight line. In this respect, precision bearings are used for both the mounting of the arm and for the mounting of the rotatable members so that both freedoms of movement are smooth. It is therefore sufficient when requiring movement of the tool 6 simply to hold the tool and pull it or push it substantially directly to the new position required. This causes any necessary sliding movement of the arm and rotation of the cup-shaped member.

It will be seen that both the cup-shaped member 14 and the concentric sleeve 26 are provided with aligned grooves forming a substantially vertically extending groove 46 facing said tool 6. This groove 46 acts to receive part of the tool 6 as it approaches the centre of its annular working plane.

The cup-shaped member 14 is eccentrically arranged relative to the spindle 24 in order to balance the weight of the tool 6 carried at one end of the arm 12, and also to enable the arm 12 to remain rigid whilst an operator is using the tool 6. In this respect, it is clear from Figure 3 that the centre of gravity of the-member 14 is on the diametrically opposite side of the central spindle 24 relative to that of the tool 6. In this respect, it is also advantageous for the wheel bearings for guiding the arm to be arranged within the cup-shaped member 14.

The vacuum tool 6 has to be connected to a source of vacuum. In the apparatus illustrated, a vacuum pump 51 is housed on the base cover 32 within a housing 50. Tubing 52, for example of plastics material, extends from the vacuum pump and is fixed to horizontally and vertically extending, communicating passages 56 drilled within the spindle 24. The passageways within the spindle open out within the concentric sleeve 26 and a length of tubing 58 is received within that space and wound around the spindle 24. A sufficient amount of tubing 58 is provided to make it unlikely that the tubing will interfere with the free rotation of the cup-shaped member 14. Aligned passageways indicated at 60 are provided through the concentric sleeve 26 and the cup-shaped member 14 and the tubing 58 is extended through these passageways and then subsequently through the interior of the arm 12.As shown, a loop of the tubing 58 is generally left external to the arm 12, again to ensure that this tubing causes no restriction on the movements of the components of the apparatus. The tubing 58 extends through the arm 12 to the end at which the tool 6 is mounted and its end is engaged on an inlet pipe 64 of the tool 6.

In the embodiment illustrated, and as preferred, the tool 6 is removably attached to the end of the arm 12. As can clearly be seen in Figure 3, the tool 6 is provided with a substantially horizontally extending bar 66 which is received within the end of the arm 12.

It will be appreciated that the screw 18, which forms the stop for the arm 12, can also be screwed into holding contact with the bar 66 to retain the tool 6 in position.

In its normal position, the tool 6 has to be retained on the arm 12 such that its nozzle 8 does not come into contact either with the turntable 36 or its cover 44, or indeed with any of the other components of the apparatus. Of course, as illustrated in Figure 4, it is essential to enable pick-up and deposit of circuit components that the nozzle be movable in a vertical direction. As also shown in Figure 4, the tool 6 is rotatable about its vertically extending longitudinal axis. The tool 6 of the preferred embodiment illustrated also has the push-button 10 at its top to control the application of vacuum to the nozzle 8. Thus, and as clearly indicated in Figure 4, the tool 6 can be used with one hand only.

A vertical section through a tool 6 is shown in Figure 5. It will be seen that the tool 6 comprises a rigid, substantially cylindrical tool body 70. The inlet pipe 64 is carried by the tool body 70 and communicates the interior of the tool body 70 with the exterior. This inlet pipe 64 may be integrally formed with or fixed to the tool body 70. The holder plate 66 is also carried by and fixed to the tool body 70. Again, this plate may be fixed to or integrally formed with the tool body 70. As can be seen from Figures 4 and 5 the holder plate 66 comprises a substantially planar rectangular plate, which is received within the arm 12, and which is extended circumferentially around the tool body 70 to form an annular flange.It will be seen from Figure 4 in particular that this annular flange is received and engaged by the diamond shaped cross-section of the arm 12 whereby the tool 6 is reliably held fixed in its vertical orientation.

A vacuum pipe 72 extends coaxially within said tool body 70 and at one end carries a needle holder 74 on which a blunt needle 76 is removably received. The nozzle 8 of the tool 6 is formed by the nozzle of the blunt needle 76. The vacuum pipe 72 is mounted for rotation relative to the tool body 70 by way of bushes 78 provided at each end of the tool body 70. At its end remote from the nozzle 8, the vacuum pipe 72 carries a sleeve member 80 which is arranged for sliding movement over and along the tool body 70.

Resilient means in the form of a spring 82 are housed within the sleeve member 80 and act to bias the sleeve member 80 to its extended position illustrated in Figure 5. The communication of the second end of the vacuum pipe 72 to atmosphere is controlled by way of a valve including a ball 84 normally seated on the second end of the vacuum pipe 72 and a ball displacing pin 86 movable by way of the push-button 10. As can be seen, the push-button 10 is slidable within a retention sleeve 88 and is resiliently biased by way of a spring 90 into its extended position illustrated.

A hole 92 is provided in the vacuum pipe 72 in a length thereof normally within the tool body 70. In the position illustrated in Figure S, vacuum applied to the inlet pipe 64, for example by way of the tubing 58, will be applied by way of the bore 92 and the vacuum pipe 72 to the nozzle 8 at the end of the blunt needle 76. In this respect, the bearings 78 at either end of the body 70 act as seals for the vacuum as does the ball 84 seated over the second end of the vacuum pipe 72. In this condition, if the nozzle 8 is brought into,c#ntact with or near to a component, by suitable movement of the members 12 and 14, and by depression of the sleeve member 80 and consequent depression of the vacuum pipe 72, the component will be picked-up by and adhered to the nozzle 8. The sleeve member 80 can then be returned to the position illustrated in Figure 5 whilst the component is moved to a different location and the sleeve member can then be depressed again to suitably locate the component. The orientation of the component can be altered by rotating the sleeve member 80 and hence the vacuum pipe 72 as necessary. Once the component has been correctly positioned, the push-button 10 is depressed such that the pin 86 moves the ball 84 away from the end of the vacuum pipe 72. This connects the vacuum pipe to atmosphere and thereby cuts off the vacuum at the nozzle 8 which deposits the component.

It will be clear from Figure 6 that the components can be housed within the turntable 36 or can be presented by cartridge arrangements as 120, detachably attached to the apparatus by way of appropriate holders 122. The printed circuit board 4 on which these components are to be arranged is held by the holding means 2.

The holding means 2 comprises a first elongate, vertically arranged bar 96 grooved to provide a substantially horizontal support surface 98. Attached to this bar 96 by way of two tie bars 100 is a second elongate, vertically arranged bar 102 also shaped to provide an appropriate support surface. Preferably each tie rod 100 is constructed from a number of telescopic sections (not shown) so that initially the horizontal spacing between the two bars 96 and 102 can be adjusted as required. In this condition, the two bars 96 and 102 extend substantially parallel to each other.

In the embodiment'illustrated, the bar 102 is affixed to the tie bars 100 by resilient means (not illustrated) which normally act to maintain the bar 102 in its correct pre-set position. However, where it is required to deposit components in sequence on a number of identically sized circuit boards, the holding means 2 illustrated is particularly advantageous. Thus, to remove a completed circuit board it is simply necessary to pull the bar 102 away from the bar 96 against the action of the resilient means to release the board. When the first board has been so released the bar 102 is allowed to resume its original position under the force of the resilient means. A further circuit board 4 can then be dropped into place on the support surfaces of the parallel bars 96 and 101.

Other suitable equipment can be supported on, or used with the apparatus as required. For example, a glue or solder applicator can be designed to be releasably held on the arm 12 in place of the tool 6 when required. Figure 6 shows the provision of optional arm rests 124 for the comfort of the operator.

It will be appreciated that variations and modifications to the apparatus as particularly described above can be made within the scope of the present invention.

Claims (33)

1. Mounting apparatus for a working tool comprising first and second support members, and holding means on one of said support members for holding a working tool, wherein said first support member is rotatable about a first axis and said second support member is linearly reciprocable in a plane substantially at right angles to said first axis, and wherein said first and second support members are interconnected such that said holding means can be subjected to a combination of their movements whereby said holding means can be moved between two points along a substantially linear path.

2. Mounting apparatus as claimed in Claim 1, wherein said first and second support members are arranged such that the holding means is movable along a substantially linear path between any two points in an annular working plane which extends substantially parallel to said plane in which said second support member is movable.

3. Mounting apparatus as claimed in Claim 1 or 2, wherein said second support member is an elongate arm slidably received in guide means of said first support member.

4. Mounting apparatus as claimed in Claim 3, wherein said guide means comprise a plurality of wheel bearings arranged to define a guide path for said support arm.

5. Mounting apparatus as claimed in Claim 4, wherein said wheel bearings are rotatably fixed to the inner surface of the base of a cup-shaped member forming said first support member, and slots or holes are provided in upstanding peripheral walls of said cup-shaped member and are aligned with said guide path along which said support arm extends.

6. Mounting apparatus as claimed in any of Claims 3 to 5, wherein said first support member is rotatable about a support spindle.

7. Mounting apparatus as claimed in Claim 6, wherein said first support member is eccentrically mounted relative to said support spindle.

8. Mounting apparatus as claimed in Claim 6 or 7, wherein the support arm is arranged to extend substantially horizontally, and said first support member is rotatable about a substantially vertically extending support spindle.

9. Mounting apparatus as claimed in Claim 8, wherein a turntable is arranged below said arm for rotation about said support spindle.

10. Mounting apparatus as claimed in any of Claims 6 to 9, wherein said holding means for the working tool is provided at or near one end of said arm.

11. Mounting apparatus as claimed in Claim 10, wherein a passage extends through said support spindle, through said first support member, and along said arm to facilitate the connection of said holding means to a vacuum.

12. Apparatus for assembling circuit components comprising mounting apparatus as claimed in any of Claims 1 to 11, wherein said holding means is arranged to hold a vacuum pick-up tool.

13. Apparatus as claimed in Claim 12, wherein said holding means is arranged to hold said vacuum pick-up tool in a predetermined and fixed orientation for movement in a working plane along a straight line.

14. Apparatus as claimed in Claim 11 or 12, wherein said vacuum pick-up tool is removably supported by said holding means.

15. A vacuum tool comprising means defining a vacuum path communicating with an outlet, means enabling reciprocable movement of the outlet along a longitudinal axis, means enabling the outlet to pivot about said longitudinal axis, and manually operable valve means carried by said tool for controlling the application of vacuum to said outlet.

16. A vacuum tool as claimed in claim 15, wherein said means enabling the outlet to pivot about said axis, enable the outlet to rotate about said axis.

17. A vacuum tool as claimed in Claim 15 or 16, wherein said vacuum path defining means comprises a pipe extending along said longitudinal axis, a first end of said pipe defining said outlet, and a second end thereof being selectively communicated with atmosphere by way of said valve means.

18. A vacuum tool as claimed in Claim 17, further comprising a nozzle removably carried by said pipe in communication with said outlet.

19. A vacuum tool as claimed in Claim 17 or 18, wherein along its length, between its first and second ends, the pipe defining the vacuum path of the tool is provided with a bore for communicating the interior of the pipe with a vacuum source.

20. A vacuum tool as claimed in any of Claims 17 to ,19, wherein the vacuum pipe extends substantially coaxially through a rigid pipe forming a tool body.

21. A vacuum tool as claimed in Claim 20, wherein the vacuum pipe is journalled within the tool body for rotation with respect thereto, and further comprising a sleeve member fixed to said vacuum pipe and slidable with respect to said tool body, said manually operable valve means being housed by said sleeve member and being operable by way of a push-button resiliently mounted on said sleeve member.

22. Apparatus for assembling circuit components comprising movable holding means for holding a working tool, and a vacuum tool as claimed in any of Claims 15 to 21 releasably mounted in said holding means.

23. Apparatus as claimed in Claim 22, wherein said holding means is supported by mounting apparatus as claimed in any of Claims 1 to 11.

24. Apparatus as claimed in Claim 22 or 23, wherein said vacuum tool is mounted such that its longitudinal axis extends substantially vertically.

25. Holding means for a circuit board comprising two elongate support members, and means for releasably maintaining said elongate members in substantially parallel relationship at a predetermined spacing, and further comprising resilient means for enabling movement of one of said elongate members relative to the other and for causing said one elongate member to be returned to a position in which said predetermined spacing is maintained.

26. Holding means as claimed in Claim 25, wherein said two elongate support members are two shaped bars connected together in spaced parallel relationship by two or more tie rods, said tie rods being adjustable in length.

27. Holding means as claimed in Claim 26, wherein a selected one of said bars is attached to each of the tie rods by the resilient means which resiliently bias said one bar towards the other bar such that said one bar is movable, against the force of the resilient means, away from the other bar.

28. Mounting apparatus as claimed in any of Claims 1 to 11 incorporating holding means for a circuit board as claimed in any of Claims 25 to 27.

29. Apparatus for assembling circuit components as claimed in any of Claims 12 to 14, or Claims 22 to 24, incorporating holding means for a circuit board as claimed in any of Claims 25 to 27.

30. Mounting apparatus for a working tool substantially as hereinbefore described with reference to the accompanying drawings.

31. A vacuum tool substantially as hereinbefore described with reference to the accompanying drawings.

32. Holding means for a circuit board substantially as hereinbefore described with reference to the accompanying drawings.

33. Apparatus for assembling circuit components substantially as hereinbefore described with reference to the accompanying drawings.