US3376851A

US3376851A - Apparatus for handling articles having paramagnetic portions

Info

Publication number: US3376851A
Application number: US512634A
Authority: US
Inventors: William A Schlemm; John E Sorbo
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1965-12-09
Filing date: 1965-12-09
Publication date: 1968-04-09
Anticipated expiration: 1985-04-09

Description

April 9, 1968 w. A. SCHLEMM ET 3,376,851

APPARATUS FOR HANDLING ARTICLES HAVING PARAMAGNETIC PORTIONS Filed Dec. 9, 1965 3 Sheets-Sheet 1 I NVENTORS WA- SCHLEMM J- 5. SORBO By (95 M A 7' TORNEV April 8 w. A. SCHLEMM ET AL 3,376,851

APPARATUS FOR HANDLING ARTICLES HAVING PARAMAGNETIC PORTIONS Filed Dec. 9. 1965 5 Sheets-Sheet 2 April 9, 1-968 w SCHLEMM ET AL 3,376,851

APPARATUS FOR HANDLING ARTICLES HAVINGPARAMAGNETIC PORTIONS Filed Dec. 9, 1965 r 5 Sheets-Sheet s q l i g 8% \a III] I I a l 1 I i I 1 I 1|{\ I IIII d if "h lllll\ I 0 I I I "1K v Q l R i s g to v i \f m I Q .1 ,ll'a, "h 1 i I y p Q ,l' ,1 I I v I I" x W! v l 1 United States Patent 3,376,851 APPARATUS FOR HANDLING ARTICLES HAVING PARAMAGNETIC PORTIONS William A. Schlemm, Fleetwood, and John E. Sorbo,

Reading, Pa., assignors to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Dec. 9, 1965, Ser. No. 512,634 Claims. (Cl. 118-321) ABSTRACT OF THE DISCLOSURE A rack-like workholder having spaced, parallel bores is loaded with articles, each of which has a flange head and an elongated paramagnetic lead extending therefrom, with the leads extending into the bores. The workholder is moved relative to a bar magnet with the flange of each article engaging a top portion of the magnet and the lead of each article held against a side portion of the magnet.

The attraction of the leads and flanges to the magnet, together with the linear motion, tends to rotate the articles in the bores so that a coating apparatus coats the entire flange of each article.

This application relates generally to apparatus for handling articles having paramagnetic portions, and more particularly to apparatus for moving such an article along a predetermined path while rotating the article about an axis thereof. Accordingly, the general objects of the invention ar to provide new and improved apparatus of such character.

Another object. of the invention is to provide new and improved apparatus for mounting a plurality of such articles for a spray coating operation.

A further object is to provide simple and efficient apparatus for mounting a plurality of semiconductor diodes having paramagnetic leads and flanges for a spray-coating operation in which a protective film is applied to the semiconductive wafers.

With the foregoing and other objects in view, apparatus in accordance with certain features of the invention includes a magnet having a surface defining a predetermined path along which an article is to be moved. The article is rotatably mounted in a carrier adjacent to the magnet such that a cylindrical section of the article contacts the surface of the magnet. The cylindrical section is of paramagnetic material, and accordingly is attracted to the surface of the magnet. A mechanism is provided for moving the .carrier in a path parallel to the surface of the magnet to move the article along the predetermined path, while maintaining the cylindrical section in contact with the magnet. The magnet is so constructed and arranged that the combination of magnetic and frictional forces between the article and the magnet causes the article to rotate as it moves along the predetermined ath. p Preferably, the magnet comprises a fixed horizontal magnet having flat upper and side surfaces which are surfaced with a nonmagnetic, frictional material to augment the frictional effect. In coating an article such as a diode having an enlarged flange of paramagnetic material at one end of a cylindrical stem or lead, the upper surface of the magnet, which is engaged by the flange, is made more strongly magnetic than the side surface which is engaged by thecylindrical section. For coating operations, an applicator is provided for applying liquid or other fluent material to the article as the article rotates and moves along the predetermined path. Preferably, the applicator moves parallel to the magnet in the opposite direction from the movement of the carrier.

Other objects, advantages and features of the invention will be apparent from the following detailed description of a specific embodiment thereof, when taken in conjunction with the appended drawings, in which:

FIG. 1 is a fragmentary perspective view illustrating the general principles of the invention, showing only the arrangement of a magnet, carrier and articles in accordance with the specific embodiment of the invention;

FIG. 2 is an enlarged perspective view similar to a portion of FIG. 1, illustrating the relative movement of one article and a liquid applicator;

FIG. 3 is a perspective view of a complete apparatus including the structure illustrated in detached form in FIGS. 1 and 2;

FIG. 4 is a vertical cross section the line 4-4 of FIGS. 3 and 6;

FIG. 5 is a fragmentary section view taken along the line 5-5 of FIG. 4, illustrating a latching mechanism for coupling the carrier with a carriage; and

FIG. 6 is a horizontal cross section particularly illustrating the drive mechanisms, taken generally along the line 66 of FIG. 4.

General principles and arrangement Referring now in detail to the drawings, and particularly to FIGS. 1 and 2, the specific embodiment of the invention is directed to apparatus for mounting a plurality of semiconductor diodes 1010 for both linear and rotational movement with respect to a liquid applicator 11 designed to spray a protective film 12 on a selected portion of each diode.

The diodes 1010 are of generally conventional construction, each including a frustoconical stud 13 on which a semiconductor wafer 14 is bonded, with a fine wire lead 16 attached to the exposed surfaceof the Wafer. The stud 13 is formed with an enlarged circular flange 17 at the base thereof, to which is attached an elongated cylindrical lead 18. Both the stud 13 and the lead 18 are fabricated of a paramagnetic material such as goldplated Kovar, an alloy of iron, nickel and cobalt commonly used in semiconductor fabrication.

In the specific embodiment, it is desired to coat the wafer 14 with a protective film 12 of a silicone varnish to protect the wafer and seal it against atmospheric contaminants. In order to assure complete coverage of the wafer, and particularly the edges thereof, it is permissible to coat the upper portion of the stud 13, but it is undesirable to have any of the coating material run or drip onto the upper surface of the flange 17. That surface should be maintained clean for a subsequent operation in which a protective housing or can (not shown) is welded to the upper surface of the flange 17 so as to cover the unit.

As illustrated in FIG. 1, the apparatus includes a fixed horizontal magnet 20 of such size that a row of the diodes 1010 may be positioned against the magnet with a portion of the flange 17 of each diode engaging and riding on an upper surface 21 of the magnet while an upper portion of the cylindrical lead 18 engages a side surface 22 of the magnet. In the specific embodiment, the magnet taken generally along 20 comprises a rectangular horseshoe magnet arranged as illustrated, with tthe flanges 17-17 contacting one pole and the leads 18-18 engaging one fiat side of the horseshoe.

The diodes -10 are rotatably mounted in a carrier 23 having a row of vertical bores 24-24 of such diameter as to receive the lower portions of the leads 18-18 for rotation; that is, the portions extending below the magnet 20. With this arrangement, the carrier 23 serves to mount the diodes for rotation about their axes and to position the diodes adjacent to the magnet as previously described. In the specific embodiment, the carrier 23 comprises an elongated bar of rectangular cross section mounted parallel to and just below the magnet.

In operation, the carrier 23 is moved in a horizontal path parallel to the side surface 22 of the magnet to move the diodes along a predetermined horizontal path defined by the side surface 22 of the magnet, while maintaining the flanges 17-17 and leads 18-18 in contact with the magnet. As the diodes move along the magnet 20, they also rotate about their axes due to the combination of magnetic and frictional forces between the diodes and the magnet. Preferably, the upper and

side surfaces

21 and 22 of the magnet are surfaced with a nonmagnetic frictional material, such as masking tape, to increase the frictional force between the magnet and the diodes and thus facilitate rotation of the diodes in response to the linear movement.

Also, it is preferred to provide a magnet so constructed that the upper surface 21 is more strongly magnetic than t the side surface 22 so as to hold the flanges 17-17 down against the magnet. Otherwise, the diodes would tend to creep up as they rotate. Thi effect is readily accomplished by using a rectangular horseshoe magnet as illustrated, in that the maximum magnetic force is inherently concentrated at the poles, one of which comprises the upper surface 21.

As illustrated in FIG. 2, the liquid applicator 11 is vertically aligned with and is horizontally spaced from the path of travel of the portions of the diodes 10-10 to be coated. Preferably, the applicator 11 is moved in a horizontal path parallel to the magnet in the opposite direction from the movement of the carrier 23, so as to spray the coating material 12 onto the entire row of diodes as they rotate and move horizontally along the magnet. In the specific embodiment, the carrier 23 is reciprocated once through a relatively short stroke, while the applicator 11 is reciprocated once in the opposite direction at a faster speed and through a longer stroke so as to sweep past all of the diodes twice. With this synchronized arrangement, the entire peripheral portion to be sprayed may readily be covered in two passes.

The applicator 11 may be any conventional spray applicator which fits the needs of the process and which has an adjustable spray which can be varied to insure uniform coating of the diodes, one satisfactory type of applicator being known as an Airbrush.

Specific arrangement of complete apparatus Referring now to FIGS. 3 and 4, illustrating a complete apparatus in accordance with the invention, the carrier 23 is mounted in the apparatus for horizontal reciprocation on a first carriage designated generally by the numeral 25. As best illustrated in FIG. 4, the article carriage 25 is located directly below and parallel to the magnet 20, so as to position the diodes 10-10 against the magnet as previously described. Prior to each spraying operation, the carrier 23 is loaded with a plurality of the diodes and is then inserted slidably (from the right side of the apparatus as viewed in FIG. 3) into a rectangular guideway 26 formed in and along the upper surface of the carriage 25 below the magnet 20.

The carrier 23 is automatically coupled to the carriage 25 for movement therewith by means of a latching mechanism 27, illustrated in FIG. 5. The latching mechanism includes a spring-loaded detent 28 which is pivotably mounted on a pin 29 located within a recess in the carriage 25. The detent 28 is normally urged by a spring 31 in a clockwise direction as viewed in FIG. 5, so that a bevelled tip 32 of the detent projects above the surface of the carriage 25. With this arrangement, the carrier 23 can be inserted manually into the guideway 26 and slid along the surface of the carriage 25, with the bottom of the carrier 23 depressing the latching detent 28 until a correspondingly tapered recess 33 in the under surface of the carrier 23 is positioned above the detent 28, at which time the spring 31 forces the detent 28 upward and into the recess 33 so as to couple the carrier 23 with the article carriage 25 thereafter.

As illustrated in FIG. 3, the magnet 20 is formed with a downwardly sloping entrance portion 34 at the right end thereof; that is, facing the direction from which the carrier 23 is inserted into the carriage 25. The sloping portion 34 serves to engage the flanges 17-17 of the diodes 10-10 as the carrier 23 is inserted, so that the flanges 17-17 travel up the sloping portion 34 and come to initial rest position on the flat upper surface 21 of the magnet, to the left of the inclined portion 34. This lifts the diodes partially out of the bores 24-24 in the carrier and properly position the diodes for the spraying operation.

Structurally, the guideway 26 is defined between a thin upstanding wall 36 at the front of the carriage 25 and a parallel fixed block 37. The block 37 is secured to a horizontal supporting platform 38 running the length of the apparatus and fixed between a pair of end walls 39-39 which are mounted on a base 40. The carriage 25 is mounted for movement to the left and right, as viewed in FIG. 3, on a pair of guide rods 41-41, which are secured between the end walls 39-39. The carriage 25 is reciprocated in generally conventional fashion by an air cylinder 42 (FIG. 6) having a piston rod 43 connected to the carriage by a bracket 44.

The carriage 25 has a rack 45 secured thereto, which meshes with a small pinion 46 that is mounted for rotation about a fixed shaft 47 of a bolt 48. A second and larger pinion 49 is secured to the pinion 46 for rotation therewith, the pinion 49 being in mesh with a second rack 51 which is secured to a second carriage 52 on which the applicator 11 is mounted. With this arrangement, a single cylinder 42 is effective to reciprocate the carrier 23 and the applicator 11 in opposite directions, and through different strokes at predetermined synchronized speeds. In the specific embodiment, the diameter ratio of the

pinions

46 and 49 is approximately 1:4, such that the applicator 11 moves at four times the speed of the diodes and the stroke is four times as long in order to enable coverage of a relatively large number of diodes 10-10, twentyfour in a specific example.

The applicator carriage 52 is mounted for reciprocable movement in spaced parallel relationship to the article carriage 25, on a pair of guide rods 53-53 similar to the rods 41-41. The applicator 11 is secured to the carriage 52 by a bracket 54 in generally conventional fashion. As is conventional for the Airbrush type of applicator 11, the bracket 54 also supports a container 56 for the liquid, as well as an air hose 58 and associated pressure regulators, etc.

In the rest position of the apparatus, as viewed in FIGS. 3 and 6, the article carriage 25 is at its maximum limit of travel to the left, and the applicator carriage 52 is fully moved to the right, engaging a stop 60. In order to start the apparatus, an air valve 61 is manually actuated to drive the piston rod 43 and thus the article carriage 25 to the right, thus moving the applicator carriage 52 to the left through the rack and pinion arrangement 45-46 and 49-51. The valve 61 also is effective to admit compressed air to the applicator 11 so as to commence the spraying operation.

In order to reverse the direction of movement of the cylinder 42 automatically at the end of the stroke, an actuating bolt 62 mounted on the applicator carriage 52 operates a second air valve 63 of conventional design. A second stop 64 is provided, which is engaged by the applicator carriage 52, to limit precisely the leftward stroke of that carriage, thus limiting also the rightward stroke of the article carriage 25. When the valve 63 is actuated, it reverses the connection of air to the cylinder 42 so as to drive the carriages and 5-2 in the opposite directions back to their initial positions. After the return stroke, the spraying operation is complete and the carrier 23 may be removed from the article carriage 25.

While one specific embodiment of the invention has been described hereinabove, it will be obvious that various modifications may be made from the specific details described, in order to suit various sizes and shapes of articles to be processed and various specific processing operations, without departing from the spirit and scope of the invention. Specifically, the construction and arrangement of the magnet and carrier are chosen to suit the particular article and process involved. In general, it is necessary that the article have a cylindrical section or stem of paramagnetic material defining the axis of desired rotation, corresponding in the example to the upper portion of the diode lead 18. One surface of the magnet (the surface 22 in the example) must :be arranged to define the predetermined path of movement which is desired for the article, and the carrier must move parallel to the surface of the magnet so as to move the article along the predetermined path while maintaining the cylindrical section in contact with the magnet so that the article can rotate as it moves along the path.

What is claimed is:

1. Apparatus for moving articles along a predetermined path while rotating each article about an axis thereof, each article having a flange and a cylindrical wire of paramagnetic material along the axis, which comprises:

(a) a magnet having a surface defining the predetermined path;

(b) a carrier having an aligned vertical row of holes for rotatably mounting the articles;

(c) means for slidably mounting said carrier adjacent to said magnet with the flanges resting on a top surface of said magnet and the wires extending therefrom in contact with a side surface of the magnet and extending into said holes; and

(d) means for moving the carrier in a path parallel to the surface of the magnet to move the article along the predetermined path while maintaining the cylindrical wires in contact with the magnet, the magnet being so constructed and arranged that the combination of magnetic and frictional forces between the article and the magnet causes the article to rotate as it moves along the predetermined path.

2. Apparatus as recited in claim 1, wherein the magnet is surfaced with a nonmagnetic, frictional material.

3. Apparatus as recited in claim 1, wherein the magnet is constructed and arranged such that the upper surface is more strongly magnetic than the side surface.

4. Apparatus as recited in claim 1, for coating a portion of the article with a fluent material, further comprising an applicator for applying the fluent material to the article as the article rotates and moves along the predetermined path.

5. Apparatus as recited in claim 4, further comprising means for moving the applicator parallel to the magnet in the opposite direction from the movement of the carrier.

6. Apparatus for spray coating like portions of a plurality of similar articles with a liquid, each article having an elongated cylindrical stem of paramagnetic material with an enlarged flange of paramagnetic material at one end of the stem, which comprises:

(a) a fixed horizontal magnet having flat upper and side surfaces of such size that a row of the articles may be placed against the magnet with a portion of the flange of each article engaging the upper surface of the magnet and an upper portion of the cylindrical stern engaging the side surface of the magnet, a lower portion of the stem of each article extending downward below the magnet;

(b) a surface layer of a nonmagnetic frictional material on the upper and side surfaces of the magnet engaged by the articles;

(c) a carrier for positioning a row of the articles adjacent to the magnet, the carrier having a row of vertical bores of such diameter as to receive for rotation the lower portions of the stems of the articles;

(d) means for moving the carrier in a horizontal path parallel to the side surface of the magnet, the magnet and frictional material being such that the combination of magnetic and frictional forces between the articles and magnet causes the articles to rotate about the axes of the stems as they move horizontally along the magnet;

(e) a liquid applicator mounted in spaced relationship with respect to the path of travel of the articles, for spraying a liquid coating material onto selected portions of the articles; and

(f) means for moving the applicator parallel to the side surface of the magnet and in the opposite direction from the movement of the carrier, so as to spray the liquid onto all of the articles as they rot-ate and move horizontally along the magnet.

7. Apparatus as recited in claim 6, wherein the means for moving the carrier and the applicator comprise:

a pair of individual carriages for mounting the article carrier and the applicator for horizontal reciprocation in spaced parallel paths;

a fluid cylinder for reciprocating a first one of the carriages; and

speed-changing gearing for converting the reciprocating movement of the first carriage into oppositely directed reciprocating movement of the other carriage, the gearing being so constructed that the applicator carriage moves faster than the article carriage and through a longer stroke.

8. Apparatus as recited in claim 7, wherein:

the carrier comprises an elongated bar of rectangular cross section, the article carriage having a matching rectangular guideway in its upper surface for receiving the carrier and permitting the carrier to be inserted slidably into that carriage; and

means are provided for latching the carrier to the article carriage for movement therewith.

9. Apparatus as recited in claim 8, wherein:

the magnet is constructed such that the upper surface is more strongly magnetic than the side surface; and

the magnet is formed with a downwardly sloping entrance portion facing in the direction from which the carrier is inserted into the article carriage, the sloping portion being arranged to engage the flanges of the articles as the carrier is inserted into the article carriage to lift the articles partially out of the bores in the carrier and position the flanges against the flat upper surface of the magnet for the spraying operation.

10. In an apparatus for rotating articles, each of which has a flange and a wire depending therefrom:

a rack having an aligned, vertical row of bore openings in a top surface of said rack;

a horizontal member having a flat upper surface and a flat side surface;

means for mounting said rack to position a portion of each of said flanges to ride upon said flat upper surface with a portion of each of the depending 3,37 6,851 7 8 wires engaging said side surface and each of said References Cited WiI'CS extending into an individual bore; means for imparting relative motion between said rack and horizontal member; and 949,330 2/1910 223541 means for imparting a drag on said portions of said 3,040,701 6/1962 Mmmck at 118-320 X flanges and engaged portions of said wires to impart 0 3,296,999 1/1967 Gamble X reactive forces that rotate said flange and wires during relative motion of said rack and horizontal mem- CHARLES WILLMUTH Pnmary Examiner her. I. P. MCINTOSH, Assistant Examiner.