WO2000070927A1

WO2000070927A1 - Device and method for bending the leads of electronic components

Info

Publication number: WO2000070927A1
Application number: PCT/NL2000/000336
Authority: WO
Inventors: Adrianus Wilhelmus Van Dalen
Original assignee: Fico B.V.
Priority date: 1999-05-19
Filing date: 2000-05-17
Publication date: 2000-11-23
Also published as: NL1012105C2; TW454432B

Abstract

The invention relates to a device for bending the leads of electronic components with two shaping parts movable relative to each other which are adapted to receive at least one electronic component for deforming, wherein one of the shaping parts comprises an engaging member displaceable relative to a shaping part base for engaging on a lead, which engaging member is connected to the shaping part base via at least one rotatable eccentric shaft. The invention also relates to a method of bending the leads of electronic components by engaging on a lead with at least one engaging member and displacing the engaging member via an eccentric along a curved path of movement.

Description

Device and method for bending the leads of electronic components

The invention relates to a device for bending the leads of electronic components with two shaping parts movable relative to each other which are adapted to receive at least one electronic component for deforming The invention also relates to a method of bending the leads of the electronic components

Bending of the leads of electronic components, in particular the leads of chips, requires a high degree of precision because very small objects are usually involved, the dimensions of which must be accurately defined after processing so as not to hinder further processing thereof (for instance building-in or assembly) This requires engaging members co-displacing with the leads, this among other things to limit the danger of damage to the lead

15

In the prior art an engaging member is driven in linear manner and urged by a guide into a curved path of movement The drawbacks of the prior art are that with a thus driven engaging member the required forces cannot be exerted in all desired directions (no or only very limited forces can be exerted more or less perpendicularly of the linear 20 drive direction) and that the device of the prior art is very susceptible to wear and fouling It has therefore not been possible heretofore to bend the leads of electronic components into all desired shapes at high speed In addition, the existing devices are expensive in use (among other reasons because it requires frequent maintenance and is prone to malfunction)

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The invention has for its object to provide an improved device and method for bending the leads of electronic components, with which the leads can be bent into all desired shapes with great speed and precision

30 The invention provides for this purpose a device of the type stated in the preamble, wherein one of the shaping parts comprises an engaging member displaceable relative to a shaping part base for engaging on a lead, which engaging member is connected to the shaping part base via at least one rotatable eccentric shaft The displaceable engaging member is preferably connected to the shaping part base via at least two rotatable eccentric shafts. By displacing the engaging member via a rotatable eccentric shaft it is possible to exert the desired forces in all directions. It hereby also becomes possible, other than in the prior art, to provide the leads with small and acute angles. Depending on the chosen construction, it can be embodied in a form which requires very little maintenance. In addition, a little wear does not have to result immediately in a drastic reduction in the bending result of the device. When the engaging member is displaced by at least two rotatable eccentric shafts, full translations can be performed herewith, which makes it possible to cause an engaging member, at the position where it engages on a lead, and the engaged lead to cover an exactly similar path. The danger of damage of the leads is also further limited in the absence of a mutual displacement between engaging member and lead.

The device is preferably provided with drive means to cause rotation of the eccentric shaft. It hereby becomes possible to cause the engaging member to make a forced movement which is controlled by the drive means. The drive means can be specifically for the purpose of rotating the eccentric shaft but it is also possible to make use of a more universal drive; an example hereof are the drive means of the ram part of a press in which the bending device is incorporated.

In a preferred embodiment the eccentric shaft is coupled rigidly to a toothed wheel, which toothed wheel engages on a gear rack, through linear displacement of which the eccentric shaft is displaceable. The device can herein be embodied such that a single gear rack engages on a plurality of toothed wheels rigidly coupled to the eccentric shafts. Still more preferably the gear rack is arranged for free displacement in an associated shaping part base such that when the shaping parts lie against each other a continued movement of the shaping parts results in the displacement of the gear rack relative to the shaping part base. The mutually meshing toothings prevent slip, so that the ratio between a determined linear displacement of the gear rack and an angular displacement of the eccentric shaft is fixed. Such a transmission is moreover structurally simple and requires only a limited accuracy for the desired purpose. It is herein possible to rotate a plurality of eccentric shafts simultaneously with a single gear rack. A full translation can thus be realized of an engaging member displaced by means of a plurality of eccentric shafts all driven by a single gear rack. Furthermore, these eccentric shafts are thus synchronized. When the bending device is embodied such that the gear rack engages on a ram part of a press in which the bending device is incorporated, it is possible in an opened position of a bending device to fix the gear rack in an end position (for instance by means of a stop). When the shaping parts of the bending device come into mutual contact, the further movement of the ram parts toward each other can result in a relative displacement of the gear rack relative to the associated shaping part base; at least one eccentric shaft is hereby rotated, which produces the desired displacement of an engaging member.

In practice the bending device preferably takes a multiple form such that a single shaping part is provided with a plurality of engaging parts. Most electromc components are provided with a plurality of leads which have to be bent with separate engaging members. With a multiple device this can take place in one process run.

For a good engagement on a lead and for a controlled end shape of the lead after the bending process, an engaging part of a first shaping part and a counter-contact part co- acting therewith of a second shaping part have substantially co-acting surface shapes.

The invention also provides a method of bending the leads of electronic components by engaging on a lead with at least one engaging member and displacing the engaging member via an eccentric along a curved path of movement. The engaging member is herein preferably displaced along a curved path of movement such that during the bending the paths of movement of engaging member and lead substantially correspond at the position where the engaging member engages on a lead. Using this method the advantages can be realized as already described above with reference to the device according to the invention.

The present invention will be further elucidated with reference to the non-limitative embodiment shown in the following figures. Herein: figure 1 shows a cross-section through the device according to the invention with two shaping parts situated at a mutual distance, figure 2a shows a cross-section through the device shown in figure 1 with a chip placed between the shaping parts in a situation where the shaping parts are mutually co-acting but the bending process has not yet been carried out, figure 2b shows a cross-section through the device and chip shown in figure 2a after performing of the bending process, figure 3 a shows a detail view of the lead of a chip with the parts of the device according to the invention engaging therewith before performing of the bending process, and figure 3b is a detail view of the lead of a chip and the parts of the device according to the invention engaging therewith after performing of the bending process.

Figure 1 shows a bending device 1 with an upper shaping part 2 and a lower shaping part 3 which can be assembled with parts of a press movable relative to each other. In lower shaping part 3 is arranged a recess 4 for receiving an electronic component with leads for bending. Under recess 4 are arranged ejecting means 5 for removing an electronic component from recess 4 after the bending process has been performed. Situated round recess 4 are standing edges 6, of which the outer sides 7 remote from recess 4 are formed so as to determine the final form of bent leads. This will be further elucidated with reference to figures 3a and 3b. Upper shaping part 2 is also provided with a recess 8 for partially accommodating an electronic component. This recess 8 is arranged in a shaping part base 9. Recesses are arranged in shaping part base 9 for passage of gear racks 10 provided with teeth. These gear racks 10 are freely displaceable relative to shaping part base 9; in this figure the shaping part base 9 is situated in a lowest position relative to gear racks 10. This position can for instance be realized by stops not shown in this figure.

Gear racks 10 are mounted on an end plate 20 in which are arranged recesses 21. In these recesses 21 are arranged pressure springs 22 which urge the protruding edges 23 rigidly connected to gear racks 10 against the edges of recesses 21. It is otherwise noted that springs 22 can also be embodied differently, for instance in the form of resilient blocks. It is also possible to connect gear racks 10 rigidly to end plate 20, although this does result in a reduced functionality. In the shown situation pressure springs 22 anyway limit the maximum pressure which can be exerted by end plate 20 on gear racks 10. Damage to gear racks 10 or the elements on which they engage can thus be prevented if upper shaping part 2 becomes jammed. The limiting is likewise advantageous when, after reaching an extreme position (see herefor figure 2b), end plate 20 is displaced even further in the direction of lower shaping part 3.

Upper shaping part 2 is further provided with four toothed wheels 1 1 which are rotatable round centrally placed shafts (not shown). Toothed wheels 1 1 are further provided with eccentrically placed openings in which eccentric shafts 12 are placed for rotation. Eccentric shafts 12 are rigidly connected to two engaging members 13 on the side remote from toothed wheels 1 1. On the side directed toward lower shaping part 3 the engaging members 13 are provided with preformed contact sides 14 which lie during operation against the leads of an electronic component. Reference is made to the following figures for further elucidation hereof.

On the side of upper shaping part 2 remote from lower shaping part 3 coupling means 15 are arranged with which simple assembly with a ram part of a press can be realized.

Figure 2a shows device 1 in a situation where a chip 16 with as yet unbent leads 17 is placed between upper shaping part 2 and lower shaping part 3. Shaping parts 2, 3 are moved so far toward each other that standing edges 6 of recess 4 and contact sides 14 of engaging members 13 lie against leads 17. The bending process has not yet been set into operation; gear racks 10 are still in the same situation relative to shaping part base 9 as shown in figure 1.

In figure 2b shaping parts 2. 3 have been moved still further toward each other; this results in bending of leads 17. The moving of shaping parts 2, 3 further toward each other results in a relative displacement of gear racks 10 relative to shaping part base 9 of upper shaping part 2. Shaping part base 9 can in any case not be moved further toward lower shaping part 3 because it already rests on non-displaceable parts of leads

17. Nevertheless urging shaping parts 2, 3 toward each other forces gear racks 10 downward, whereby toothed wheels 1 1 are rotated. The rotation of toothed wheels 1 1 round the central rotation shafts (not shown) results in a relative displacement of eccentric shafts 12 relative to shaping part base 9 and thus simultaneously in a relative displacement of engaging members 13 coupled to the eccentric shafts. The resulting translation of engaging members 13, and in particular the preformed contact side 14 thereof, results in the desired bending of leads 17. This process is further illustrated with reference to figures 3a and 3b.

Figure 3a shows a detail view of the situation depicted in figure 2a. A chip 16 with leads 17 is partially accommodated in recesses 4 and 8. The standing edge 6 of recess 4 lies against the underside of a lead 17 and a supporting edge 18 of shaping part base 9 lies against the top side of the same lead 17. Engaging member 13 is not yet situated in contact with lead 17. Shown with broken line 19 is the path of movement through which engaging member 13 will progress in order to reach the position shown in figure 3b.

Figure 3b is a detail view of the position after the bending process has been completed (after progression through path of movement 19). The preformed contact side 14 of engaging member 13 connects onto the bent lead 17. During performing of the bending process no relative displacement takes place between contact side 14 and lead 17. The advantage hereof is that damage to lead 17 is less likely to occur than if a shearing force were to occur between contact side 14 and lead 17. As it progresses through the path of movement 19 the engaging member 13 can everywhere exert a sufficiently great force on lead 17, even in the final part of the path, even though the direction of movement is for a major part directed inward (i.e. toward a central axis of device 1).

Although the device is elucidated with reference to only a single embodiment, it will be apparent to all that the invention is in no way limited to the described and shown embodiment. On the contrary, many other variations are possible for a skilled person within the scope of the invention.

Claims

1 Device for bending the leads of electronic components with two shaping parts movable relative to each other which are adapted to receive at least one electronic component for deforming, wherein one of the shaping parts comprises an engaging member displaceable relative to a shaping part base for engaging on a lead, which engaging member is connected to the shaping part base via at least one rotatable eccentric shaft.

2. Device as claimed in claim 1 , wherein the displaceable engaging member is connected to the shaping part base via at least two rotatable eccentric shafts

3. Device as claimed in claim 1 or 2, wherem the device is also provided with drive means to cause rotation of the eccentric shaft.

4. Device as claimed in any of the foregoing claims, wherein the eccentric shaft is coupled rigidly to a toothed wheel, which toothed wheel engages on a gear rack, through linear displacement of which the eccentric shaft is displaceable

5. Device as claimed in claim 4, wherein a single gear rack engages on a plurality of toothed wheels rigidly coupled to eccentric shafts

6 Device as claimed in claim 4 or 5, wherein the gear rack is arranged for free displacement in an associated shaping part base such that when the shaping parts e against each other a continued movement of the shaping parts results in the displacement of the gear rack relative to the shaping part base

7. Device as claimed in any of the foregoing claims, wherein the device takes a multiple form such that a single shaping part is provided with a plurality of engaging parts.

8. Device as claimed in any of the foregoing claims, wherein an engaging part of a first shaping part and a counter-contact part co-acting therewith of a second shaping part have substantially co-acting surface shapes.

9. Method of bending the leads of electronic components by engaging on a lead with at least one engaging member and displacing the engaging member via an eccentric along a curved path of movement.

10. Method as claimed in claim 9, wherein the engaging member is displaced along a curved path of movement such that during the bending the paths of movement of engaging member and lead substantially correspond at the position where the engaging member engages on a lead.