GB2142865A - Film micromanipulator - Google Patents

Abstract

A film or sheet micromanipulator comprising a pair of like arms 16 spaced apart in parallel relationship and pivotably and slidably moveable within respective bearings 11 in a support frame 4, 1a, respective one ends 17 of the arms being provided with vacuum heads 19 whereby film or sheet material may be securely held when a vacuum is applied to said heads, the other ends of the arms being connected to a linkage 6, 15, whereby said arms may be moved together or separately within their bearings, the linkage being coupled to manually operable levers 7,8 having movement reducing leverage or gearing whereby the heads may be advanced from or retracted to the support frame together or separately and may be moved laterally with respect to the frames. <IMAGE>

Description

SPECIFICATION Film manipulator This invention relates to a film micromanipulator for the accurate positioning of photographic or transparent film sheets or the like prior to punching registration or tooling holes therein.

In the production of printed circuit boards with more than one conducting layer, and in colour printing, there can be a requirement to punch registration or tooling holes into film sheets with the patterns on the sheets registered accurately together.

A known method of achieving such accu rate punching of registration holes is on a semi-retracting punch, which commonly takes the form of two or more punches 100 mounted on one edge of a lightbox 101, on which the film sheets to be punched can rest on an illuminated glass plate 102, as shown in Fig. 1.

The punches 100 work upwards through the sheet, and when a first sheet 103 has been punched (usually a "master" film of the set), the punch pins 104 are partially retracted so that they remain in the holes punched in the sheet 103 with their working faces just below the face of the sheet but with the pins still in engagement in the holes in the film, as shown in Fig. 2.

The second sheet to be punched is then inserted in the punch jaws over the first sheet, and when the patterns on the two film sheets are aligned to the required accuracy, the punch is operated, and the holes in the second sheet are punched. This process can be repeated for all sheets in the set.

In printed circuit board work, it is common to use a negative master film, over which positive patterns can be aligned to give totai blackness when the essential elements of the pattern are aligned perfectly. Any misalignment allows light to pass and is easily detected. By such means, tooling alignment to better than 0.01 mm may be achieved.

A known disadvantage of this system is that it can be difficult to move the upper film sheet (to be punched) over the lower sheet in the minute increments necessary to achieve perfect alignment.

A known method of handling such film sheets comprises mounting the upper film sheet on a frame, the position of which can be accurately controlled by micrometer adjusting screws.

Such known micrometer adjusting systems have several disadvantages.

They are expensive to make, and are not quick to use. If the sheet to be aligned is not positioned initially within the operating range of the screws, alignment times can be very protracted as the sheet is re-positioned and the micrometer screws are run back.

This invention offers a system which can be made very cheaply without need for any accurate machining, and is very quick to use.

According to the invention there is provided a film or sheet micromanipulator comprising a pair of like arms spaced apart in parallel relationship and pivotably and slidably moveable within respective bearings in a support frame, respective one ends of the arms being provided with vacuum heads whereby film or sheet material may be securely held when a vacuum is applied to said heads, the other ends of the arms being connected to a linkage whereby said arms may be moved together or separately within their bearings, the linkage being coupled to manually operable levers having movement reducing leverage or gearing whereby the heads may be advanced from or retracted to the support frame together or separately and may be moved laterally with respect to the frames.

An embodiment of the invention will now be described with reference to Figs. 3 to 5 of the accompanying drawings which are a perspective view, a plan view and a side view respectively of a micromanipulator.

The micromanipulator can be mounted on the back of a punch, such as that shown in Fig. 1, with its operating heads passing beside the punch jaws; it can be mounted on one edge of the lightbox, or it can be mounted over the glass face at either side or in the front.

With reference to the drawings, the micromanipulator is in the form of a box 1 which can be mounted, by means of a mounting plate 2 with supporting struts 3, on a side of the lightbox, or by omitting items 2 and 3 and making the vacuum heads, 19, deeper, the base 1 a can be mounted over the glass of the lightbox.

In the embodiment shown, the base la carries near each end brackets 4, which project slightly to pass between the heads of the punch. These brackets contain interference fit resilient low friction, e.g. PTFE bushes 11, through which arms 16 can slide and/or pivot. The inner ends of the arms 1 6 are connected via low friction bushes 1 2 to levers 7, and also pass through similar bushes on a carrier 6, which rests on the base 1a, and on which the levers 7 rest. The outer ends of the levers 7 are restrained at a set distance back from the ends of the brackets 4 by swing links 14 which can turn without shake in low friction bushes 10 and 1 2a.

The outer ends of the arms 1 6 carry independently controllable vacuum heads 1 9 which are connected via flexible vacuum pipes 23 to a vacuum control tap 22. In practice the arms may be a composite structure, made up of rods 1 6 which slide and pivot in the bearing bushes 11 and leaf springs 1 7 which affixed to the rods 1 6 by clamp plates 18, thereby providing vertically resilient mount ings for the heads 1 9. The levers 7 carry handles 9 by which the levers can be pivoted about their pivot pushes 1 2a. The carrier 6, on which the levers 7 rest, is connected by a bush 1 2b and link 1 5 to another lever 8, via bush 1 2c, which in turn pivots about a pin 1 3 passing through the bore 1 a.Lever 8 has a handle 9a. Thus movement of the handle 9a results in a very small movement of the carrier 6 from side to side, with a consequent small movement of the vacuum heads 1 9 from side to side. Movement of either of the handles 9 results in a very small movement of the respective vacuum heads 1 9 forwards or backwards from the plane of the mounting plate 2. When the micromanipulator is in use it is quick and easy to first secure a film sheet to the vacuum heads in the approximate desired position and then to manoeuvre the sheet precisely by manipulation of the handles 9 and 9a until the final accurate position is achieved. The film sheet may then be punched.

To assist the securing and subsequent manoeuvring of the film sheet the micromanipulator may incorporate a lifting machanism in the form of levers 20 which pass alongside the arms 1 6 and under the leaf springs 1 7 and which pivot in holes in the brackets 4.

The levers 20 can then be used to raise and lower the vacuum heads. The levers 20 engage in notches in pillars 21 to lock them in either the raised or lowered position. The PTFE bearings 11 through which the arms 1 6 and levers 20 pass are secured in the brackets 4 by cover plates 5.

Claims (9)

1. A film or sheet micromanipulator comprising a pair of like arms spaced apart in parallel relationship and pivotably and slidably moveable within respective bearings in a support frame, respective one ends of the arms being provided with vacuum heads whereby film or sheet material may be securely held when a vacuum is applied to said heads, the other ends of the arms being connected to a linkage whereby said arms may be moved together or separately within their bearings, the linkage being coupled to manually operable levers having movement reducing leverage or gearing whereby the heads may be advanced from or retracted to the support frame together or separately and may be moved laterally with respect to the frames.

2. A micromanipulator according to claim 1 wherein the bearings are provided as interference fit resilient low friction bushes.

3. A micromanipulator according to claim 1 or 2 wherein the arms are composite structures comprising rod sections which slide and pivot in the bearings and leaf spring sections which carry the vacuum heads and provide for vertical movement of the heads.

4. A micromanipulator according to any preceding claim including means for mounting the micromanipulator on the side of or above a light box or the like.

5. A micromanipulator according to any preceding claim wherein said linkages comprise levers of unequal throw.

6. A micromanipulator according to any preceding claim incorporating lockable lifting means for each of the vacuum heads.

7. A micromanipulator substantially as described with reference to Figs. 3-5 of the accompanying drawings.

8. A method of manufacturing a printed circuit board having more than one conducting layer, comprising providing a first sheet defining a first circuit configuration, providing a second transparent sheet defining a second circuit configuration, placing the sheets one over the other and accurately aligning the first and second configurations by gripping one of the sheets using a vacuum gripping device and operating a linkage mechanism coupled to the device and having a high-ratio lever, to move said one sheet into alignment, and using the aligned sheets to print the desired combined circuit configuration in the board.

9. A method of manufacturing a printed circuit board substantially as described herein with reference to the accompanying drawings.