HIGH VOLUME CRYSTAL PLATING APPARATUS AND METHOD

Abstract: A high crystal plating apparatus (50) includes a carousel (90) with fingers (92) and a mask (110) for holding and masking twenty or more crystals (204) in circuits (200) within a vacuum chamber (52). Each circuit (200) is sequentially positioned to allow plating of a crystal (204) and measurement of its frequency. The mask (110) has an alignment peg (112) adapted to fit into alignment hole (102) on the back (94) of the carousel to allow the mask to fit within the fingers (92), so that the tapered apertures (116) of the mask are positioned correctly for the plating. In the method of using the apparatus (50), plating is terminated when a desired value of crystal frequency is measured. A contactor (230) accepting variable thickness pins or lead wires can be used to establish electrical contact for measuring crystal frequency.

Description: HIGH VOLUME CRYSTAL PLATING APPARATUS AND METHOD" BACKGROUND OF THE INVENTION Field of the Invention This invention relates to apparatus for plating crystals and, more particularly, to apparatus for conducting multiple crystal plating operations in a high vacuum environ¬ ment. Description of the Prior Art The calibration of crystals for electronic circuits requires plating of individual crystals in order to change the frequency of the crystal to desired performance specifications As the need for more and more calibrated crystals has increase the necessity for high volume crystal plating apparatus has increased. Initial crystal plating was done on an individual basis with crystals placed in bell jars after being masked. The bell jars would then be evacuated and plating would occur by vaporization of a plating metal adjacent to the crystal. The procedures involved lengthy times for evacuating the bell jars and masking the crystals. Improvements in the crystal plating apparatus dealt with reducing the volume within the plating chamber to reduce the time for evacuating the chamber in order for the plating t occur. Other improvements related to the measurement of the ' frequencies of the crystal during the plating process. However, the crystal plating process was still a relatively small batch process in which a few crystals at a time could be produced. SUMMARY AND OBJECTS OF THE INVENTION The present invention sets forth a high volume crystal plating apparatus in which twenty or more individual crystals or individual clock circuits incorporating crystals can be mounted in a fixture and individually sequentially positioned for plating by vaporization of a plating material in the high vacuu chamber. The crystals to be plated, whether individually mounted or plated as part of a clock circuit, are mounted externally in the chamber and masked in a single operation. They are then positioned within the chamber for the sequential plating operation. The apparatus also sets forth a contacting means by which individual crystals and/or circuit chips having pins or wires can. be contacted for purposes of powering the crystal or measuring the parameters of the crystal without deteriorating the leads from the crystal or the board on which the crystal is mounted. The invention also provides for a contact for pins or leads from crystals and or circuits incorporating crystals in which positive contact to a conductor is made by means of rolling contact between the wire or pin ' and a conducting surfac The contactor can receive relatively thick pins or relatively thin lead wires without any change in the contactor. Also set forth is a method for plating crystals individually or incorporated in circuits which method includes the steps of loading a batch of crystals and masking a batch in a single operation, mounting the loaded and masked crystals in a chamber, and sequentially positioning the crystals within the chamber for vapor plating of a metal on the crystal, and then removing the plated crystals from the chamber. Accordingly, it is an object of the present invention plate a relatively high number of crystals or crystal-utilizing circuits in a single batch in a vacuum chamber. Another object of the present invention is to provide a high capacity crystal plating apparatus which allows for quick and easy loading and unloading of crystals or circuits incorporating crystals for purposes of plating. Yet a further object of the present invention is to provide a high capacity crystal plating apparatus which allows for masking a relatively high number of individual crystals or circuits incorporating crystals in a single operation for purposes of plating the crystals. Another object of the present invention is to provide a high capacity crystal plating apparatus which has relatively simplified construction. A further object of the present invention is to provide ^ a high capacity crystal plating apparatus which is reliable in operation. Another object of the present invention is to provide a high capacity crystal plating apparatus which is easy to use Still another object of the present invention is to provide a high capacity crystal plating apparatus which requir relatively little maintenance. A further object of the present invention is to provide a high capacity crystal plating apparatus which uses relatively low quantities of plating metals to accomplish the plating of the crystals . Yet another object of the present invention is to provide a high capacity crystal plating apparatus which mainta a reserve supply of plating metals to ensure that the apparatus will not run out of plating metals during the plating cycle. Another object of the present invention is to provide a high capacity crystal plating apparatus which allows for supplying fresh quantities of plating material during the running of a plating batch, if necessary. A further object of the present invention is to provide a high capacity crystal plating apparatus which affords easy access for loading and unloading batches of crystals and/o crystal circuits to be plated. Yet another object of the present invention is to provide a high capacity crystal plating apparatus which uses a single unit to mask all of the items to be plated in a relative quick and easy masking procedure. A further object of the present invention is to provide a high capacity crystal plating apparatus which has a relatively short cycle time between plating operations. Another object of the present invention is to provide a high capacity crystal plating apparatus which provides a vertical spray pattern during the plating operation to minimize contamination of the area to be plated. Still another object of the present invention is to provide a high capacity crystal plating apparatus which can plate either individual crystals or crystals which are incor¬ porated in entire circuits. Yet a further object of the present invention is to provide a high capacity crystal plating apparatus which does not require extended pump down between plating cycles. Still another object of the present invention is to provide a high capacity crystal plating apparatus which can produce rapid evacuation of the plating chamber. Still a further object of the present invention is to provide a high capacity crystal plating apparatus having contac which can engage pins or lead wires from crystals without damag to these items. Yet a further object of the present invention is to provide a high capacity method for plating crystals in which a large number of crystals can be positioned for plating remotely from the plating chamber. Another object of the present invention is to provide a high capacity method for plating crystals where a large numbe of crystals can be masked for plating in a single operation. A still further object of the present invention is to provide a high capacity method for plating crystals in which a relatively large batch of crystals can be individually plated in a sequential operation while measurements are taken of the crystal frequency during the plating process. Yet another object of the present invention is to provide a high capacity method for plating crystals where a large batch of crystals can be plated in a high vacuum chamber with relatively little vacuum pumping required during the actu plating process of the entire batch. A further object of the present invention is to provide a high capacity method for plating crystals which has relatively short period of time between individual sequential plating operations. Further, it is an object of the present invention to provide a contactor for conductively receiving pins or wires without a compressive engagement. Another object of the present invention is to provide a contactor for conductively receiving pins or wires which provides a constant urging force to contact the pin or wire with a conductive surface. A further object of the present invention is to provide a contactor for conductively receiving pins or wires which can receive a wide variety of sizes of pins and/or wires. Yet another object of the present invention is to provide a contactor for conductively receiving pins or wires which will not wear out from repeated use. Another object of the present invention is to provide a contactor for conductively receiving pins or wires which establishes contact without the use of frictional engagement. A further object of the present invention is to provide a contactor for conductively receiving pins or wires which can contact fine wires without bending the wires. Another object of the present invention is to provide a contactor for conductively receiving pins or wires which is simple in construction. Yet another object of the present invention is to provide a contactor for conductively receiving pins or wires which is relatively inexpensive to fabricate. A further object of the present invention is to provide a contactor for conductively receiving pins or wires which is relatively durable. Another object of the present invention is to provide a contactor for conductively receiving pins or wires which is easy to handle. Yet a further object of the present invention is to provide a contactor for conductively receiving pins or wires which is not affected by heat. Still another object ' of the present invention is to provide a contactor for conductively receiving pins or wires which will not clog or jam. A further object of the present invention is to provide a contactor for conductively receiving pins or wires which can handle fine wires or relatively thick pins with the same unit and without any change to the contact. Other objects and advantages will be apparent from the following description of the invention, the novel features being particularly pointed out hereinaf er in the claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view showing the high volume crystal plating apparatus of the present invention? Figure 1A is a partial section broken away along lines 1A-1A of Figure 1; Figure 2 is a schematic view showing a clock circuit positioned behind the mask ready for plating; Figure 3 is an exploded perspective view of the device shown in Figure 1 with the chamber door open; Figure 4 is a partial section taken along line 4-4 of Figure 1; Figure 5 is a rear view of the apparatus shown in Figure 1; Figure 6 is a partial exploded view of the clock circuit mounted in the apparatus for plating taken from the rear; Figure 7 is a view along line 7-7 of Figure 4; Figure 8 is an exploded view of a contact pin used in the invention; Figure 9 is a sectional view along line 9-9 of Figure 8; Figure 10 is a partial perspective view of the device used for carrying the plating material; Figure 11 is a partial perspective view of the mask apparatus shown in Figure 3; Figure 12 is an exploded perspective view, similar to Figure 1, of another embodiment of the invention; Figure 13 is a view similar to Figure 4 showing individual crystals mounted for plating; and Figure 14 is an exploded view, similar to Figure 6, showing individual crystals mounted for plating. DETAILED DESCRIPTION OF THE INVENTION Referring to the Figures 1 and 3, a high volume crystal plating apparatus, generally indicated at 50, consists of a chamber 52 having a door 54 that is connected to the chamber by means of a displaceable hinge arrangement 56 and which provides a seal when evacuated by means of an o-ring 58. The chamber rests on a tube, or conduit, 60 connected to a source of vacuum, not shown. Adjacent to the chamber 52 is frequency measuring apparatus, generally indicated at 70, whic is connected into the chamber by various lead wires 72 which are partially broken away and which will be explained later. As 'seen from Figure 3, the vacuum tube 60 has a top end 62 which extends through the cylindrical wall of the chamb 53 to evacuate the chamber when the door 54 is closed. An aligning device 55 helps position the door 54 when it is in th closed position as shown in Figure 1A. The chamber is sealed wherever necessary in order to prevent any air from entering the chamber during the plating procedure. The devices to be plated are mounted on a circular device, referred to as a carousel and generally indicated at 9 as shown in Figure 3 having a plurality of fingers 92 extendin parallel to the axis of rotation near the periphery of the carousel. The carousel has, as we mentioned, a circular back portion 94 with a plurality of air passages 96 for venting, an rotates on a central hub 98. As can be seen, a series of numbers are inscribed in the back 94 of the carousel which indicate stations which are formed between adjoining fingers 92. A mask, generally indicated at 110, having an alignment peg 112 adapted to fit into alignment hole 102 on the back 94 of the carousel allows the mask to fit within the fingers of the carousel so that the cylindrical section of the mask 114 fits inside the fingers 92, and is positioned by means of the aligning peg 112 and aligning hole 102 so that the tapered apertures 116 in the cylindrical portion 114 of the mask are positioned over the location of where the crystal will be to provide for proper plating of the crystal. As seen in Figures 3, 4 and 11, the plating apparatus, generally indicated at 120, is a housing mounted to the door 54 of the chamber and is mounted on a shaft 122 in the door of the chamber 54. The shaft can be placed in two positions by means of a handle 124 so that either of two boats 126 and 128 can be actuated. Boat 126 is the boat closer to the door and boat 128 is the boat positioned further from the door. Power lines 130 bring current to the plating apparatus to heat the boats which in turn vaporizes the blobs of plating metal 132 located in each of the boats so that, depending on which boat is being actuated, the metal will be vaporized and will spray upward against the inside of the mask 114 and throug the aperture 116 to plate the crystal. As shown in Figure 4, a crystal circuit, generally indicated at 200, has a plate 202 on which a crystal 204 is mounted as part of a circuit. Pins 206 extend from the back of the plate to connect the circuit for its intended use after manufacturing and also for purposes of connecting the circuit to the frequency measuring device during the plating operation. As shown in Figure 4, a deposit of plating material 208 forms on the face of the crystal adjacent the mask as a result of the plating operation. Each of the carousel fingers has two plastic mounting bushings 104 on opposite sides of finger 94. Each of the bushings 104 is positioned in a cylindrical groove of mating configuration in the sides of the fingers 92 and each of the bushings, in turn, has a mounting groove 106. Therefore, the adjacent mounting bushings on adjacent mounting fingers 92 for a receptacle for holding the sides of the plate 202 of the crystal circuit. This relationship is shown most clearly in Figure 6. The cylindrical deformation 93 in the opposing side of fingers 92 is more than semicircular in nature so that the mounting bushing 104 cannot fall out. As seen in Figure 6, mask 110 has a flange 108 which fits over the mounting fingers 92 to prevent the crystal circu 200 from falling out. A small wing screw 100 threads into the side of the carousel to bear against the cylindrical portion of the mask t hold the mask in place. As can readily be seen, the crystal circuits 200 can be loaded in a carousel outside of the chamber and the mask then aligned and fitted. The entire carousel is then mounted on the hub 142 extending into the chamber and is held in place by any convenient means such as a detent. The carousel is indexed within the chamber for sequential plating by means of an indexing wheel 144 mounted on the same hub 142. As seen in Figure 5, indexing wheel 144 is mounted to hub 142 by means of a one-way roller-bearing or roller clutch 146. The clutch itself is actuated by means of a pneumatic cylinder 148 having two ports and which, in turn, is connected to a mechanical linkage 150 so that the oscillating arm of the pneumatic cylind 148 will draw the linkage 150 connected to the one-way clutch 1 to turn the axle or hub 142 counterclockwise as seen from the rear. The one-way clutch 146 will slip when the double acting cylinder moves in the opposite direction to extend the arm. After the double acting horizontal cylinder 148 rotates the hub to the approximate location, a second cylinder, vertically disposed, indicated at 152, extends a rod 154 or shot key so that the end of the rod will enter into the appropriate counter board hole 156 in the indexing wheel to accurately position the indexing wheel. This, in turn, will turn the hub 142. Connect to hub 142 is a turning wheel 160 which is connected to the carousel by a series of pins 162 and which connects with aligni passages 108. A plurality of passages 164 are formed in turning wheel 160 for purposes of being able to evacuate the space behind the turning wheel to the vacuum tube. As seen in Figures 1, 7 and 4, after the carousel has been indexed to position the crystal circuit 200 for plating by the plating apparatus, a contacting assembly, generally indicate at 170, will contact the pins of the circuit to frequency measuring equipment, generally indicated at 70, to measure the frequency of the crystal as the plating occurs in order to auto¬ matically stop the plating process at the proper parameters. The contactor assembly consists of a double acting cylinder 172 having two air passages 174 and 176 to raise and lower a shaft 178 to which four contactors 180 are connected. Various wires 182 connect each of the contactors to the necessary equipment. They, in turn, may lead to wire leads 72 which connect to the frequency measuring equipment. The contactors have a slightly depressed or trumpet-shaped bottom and are spring-loaded (not shown) so as to contact the ends of pins 206 to make the appro¬ priate contact. A sequencing micro-switch 164 is connected to the arm of indexing cylinder 148 so that the aligning or vertica cylinder 152 will not position aligning rod 154 until after the indexing cylinder 148 has been actuated. The same sequencing micro-switch also ensures that the contactor cylinder 172 will not be actuated to lower the contactors until after the vertical aligning cylinder has been actuated. As seen in Figure 7, the entire contactor assembly 170 sits on a housing base 184 with two intermediate layers 186 and 188 respectively adjacent to and remote from the base. A grease fitting 190 is provided for lubrication of the shaft 178. While the embodiment of the invention discussed so far has dealt with plating of crystals in circuits which have relatively heavy pins and are relatively to contact, the presen apparatus can also be used to plate individual crystals having relatively fine wires. In order to accomplish this, an adaptiv contactor is utilized, as shown in Figures 8 and 9. The adapti contactor, generally indicated at 230, is formed from a cylinde 232 of conductive material such as brass. The cylinder has a stepped axial bore having a larger diameter 234 at the upper portion and a smaller diameter 236 at the lower portion or remote portion of the cylinder. Two ballbearings of different size, namely a smaller ballbearing 238 and a larger ballbearing 240 respectively, are positioned in counter-sunk radial bores 242 and 244 for the smaller and larger balls respectively. An undercut portion 24 of the outer diameter of the cylinder is surrounded by elastic tubing 248 to hold the balls in their respective bores. Therefore, as can be seen from Figure 9, the radial bores are counter-sunk so that a portion of the ball can extend into the bore but that the entire ball cannot fit into the axial bore. Therefore, as can be seen in Figure 9, the larger ball 240 mounted in the larger radial bore 244 extends into th smaller axial bore 236 and is held in that position by surgica tubing 248. A relatively thin lead wire, as from a crystal, can be placed down the larger bore 234 and extend into the smaller bore 236 where it will be urged by the larger ball 240 against the side wall of the smaller bore 236 into conducting contact with the cylinder 232. Note that there is little or no friction involved in this situation. There is rolling contact between the larger ball 240 and the fine wire. The wire can be inserted and removed without undue difficulty and without degrading the wire. Similarly, a relatively large pin, as shown in the dotted lines, could be placed into the large bore 234 where it would be contacted by the small ball 238 and held against the wall of the cylinder 232 by the resilience of the elastic tubing 248. Note, the shoulders of the undercuts in the cylinder 232 maintain the position of the elastic tubing 248. Figures 12, 13 and 14 show the apparatus with a different embodiment of the carousel to enable the apparatus to plate individual crystals rather than circuits which incorporat crystals . As shown in Figures 12 and 13, the carousel, generally indicated at 1090, has an annular cylindrical section 1092 which takes the place of the fingers previously mentioned. The end face 1094 of circumferential cylindrical portion 1092 has a plurality of holes 1096 formed therein each of which has fitted into it a tubular plastic bushing 1098. The adaptive contactor 230, previously discussed, is adapted to fit into bushing 1098 to receive the lead wires 1100 of a crystal assembly, generally indicated at 1102, having a crystal 1104 mounted on a base 1106. A plurality of counter-sunk passages 1108 intersects the adapti contactor 230 at a point on the cylinder 232 that is not covered by the elastic tubing 248 in order to contact the adaptive contactor and therefore create a conductive path from the leads of the crystal to the frequency measuring apparatus. The mask 1110 operates in the same manner, with the crystal 1104 being positioned behind the aperture in the mask for plating in the index sequential manner as previously described. Now, having described the apparatus by which the plating occurs, the method by which the plating occurs is relatively straightforward. It consists, basically, of loading circuits containing crystals or crystals themselves onto the carousel. The carousel when loaded with a relatively large num of items to be plated, as for example twenty or more, is then masked in a single operation to mask all of the items to be plated by insertion of the masking ring. The masking ring is aligned and then secured to the carousel to properly position the apertures over the items to be plated. The combined holder and mask containing the items to be plated is then mounted in the chamber on the turning wheel and hub. The door of the chamber is then closed and the chamber is evacuated by the vacuum means. The carousel is then indexed to the first positi at which plating is to occur. After the carousel is accurately aligned, the contacting means contact the leads or pins leading to the crystal to be plated, whether individually or in a circuit. Current is then provided to the plating apparatus to melt the plating metal and disperse the plating metal in a directed shower against the mask so that the plating material will pass through the aperture to plate the surface of the crystal and thereby affect the frequency of the crystal. While plating occurs, the frequency is measured by means of measurinσ means until the desired parameters are reached. At that time, the plating is stopped and the carousel is then indexed to the next position at which time contacting, plating and measuring occur again until the plating is stopped and, once again, the carousel is further indexed. After all of the stations in the carousel have been indexed and the plating operation accomplis the vacuum in the chamber is released, the door of the chamber is opened, and the carousel and mask with the now plated cryst are dismounted and removed from the chamber. From the description of the invention set forth above, the many and numerous advantages of the invention can be clear seen. While specific embodiments of this invention are described and -shown herein, it is to be understood that other embodiments may be resorted to without departing from the spir and scope of the invention.

Claims: WHAT IS CLAIMED IS: 1. Apparatus for plating crystals comprising: a housing adapted to be connected to a source of vacuum; a chamber within said housing; a carousel for holding a plurality of objects to be plated; a mask adapted to coact with said carousel to mask one or more items to be held in said carousel; means to mount said carousel and said mask in said chamber; plating means disposed in said chamber; means to index said carousel to position said items to be plated for coaction with said plating means ; and means to seal said chamber with said carousel and mask disposed therein. 2. The apparatus of Claim 1 further comprising contactor means coacting with said chamber to contact said items to be plated when said items have been indexed for plating. 3. The apparatus according to Claim 1 further comprising frequency measuring means coacting with said chamber to measure the frequency of said item to be plated during the plating process. 4. The apparatus according to Claim 1 wherein said carousel means comprises a plurality of fingers, said fingers adapted to hold circuits incorporating crystals. 5. The apparatus according to Claim 1 wherein said carousel means includes holding means to hold individual crystals in coactive relationship with the contacting means for contacting said crystal during plating. 6. The apparatus according to Claim 1 further comprising power means extending into the chamber to vaporize plating material for coating of said items in said chamber. 7. The apparatus according to Claim 1 further comprising door means to seal said chamber means. 8. The apparatus according to Claim 1 wherein said index means comprise means to rotate said cylinder; and means to 75 align said cylinder. 9. The apparatus according to Claim 8 wherein said means to align said carousel comprise: an aligning wheel operatively connected to said carousel; an aligning rod; and means to engage to said aligning rod to extend said rod into and out of a plurality of coacting depressions in said wheel to accurately position said wheel. 10. A method for plating crystals and the like comprising: loading a plurality of crystals on a device adapted to rotate; masking said crystals rotated by connecting a mask to said device adapted to rotate; mounting said rotating device and mask on positioning means in a chamber; sealing said chamber; indexing said crystal holder adapted to rotate in the chamber; contacting said crystals mounted in said rotating means for measurement of frequency thereof; plating said crystals until desired frequency is obtained; and indexing said rotating device holding said crystals to the position for the plating of the next crystal. 11. The method according to Claim 10 wherein before the step of plating is the step of providing power to plating materials located within the chamber. 12. The method according to Claim 10 wherein the step of masking consists of placing a mask in cooperative relationship with the means holding the items to be plated which is meant t be rotatably mounted in a chamber. 13. The method according to Claim 10 wherein the step of mounting the means holding the items to be plated consists of mounting a carousel on a hub and placing it in the chamber the closing the door to the chamber. 14. The method according to Claim 10 wherein the step of inde includes the step of rotating the chamber and then the step of aligning the chamber. 15. The method according to Claim 14 wherein the step of indexi the chamber consists of rotating the chamber so that the items to be plated will be rotated in a vertical plane with the item to be plated at the 12 o'clock position. 16. An adapter—contactor for connecting pins and/or lead wires from crystals to a conductive path comprising: a cylinder of conductive material; an axial bore in said cylinder adapted to receive a conductive lead; a radial bore in the wall of said cylinder intersecting said axial bore; a circular object disposed in the bore intersecting said axial bore and partially obscuring said axial bore; and means resiliently urging said circular object into said axial bore, to thereby urge any object in said axial bore against the opposite wall from the bore intersecting said axial bore. 17. The apparatus according to Claim 16 wherein said circular object consists of a ballbearing means. 18. The apparatus according to Claim 16 wherein said bore intersecting said axial bore comprises a tapered bore adapted to receive a ballbearing to partially extend into the axial bor 19. The apparatus according to Claim 16 wherein said means to siliently urge " said circular object comprise elastic tubing mea disposed about the outer wall of the cylindrical conducting sur 20. The apparatus according to Claim 16 wherein: said axial bore has a step therein to form a larger diameter bore and a smaller diameter bore; a plurality of passages in the wall of said cylinder, one of said of said plurality of bores of the wall of said cylinder contacting the larger bore, another plurality of bores contacting the smaller bore. 21. The apparatus according to Claim 20 wherein a larger ball disposed in the bore contacting the smaller axial bore and a smaller ball in the bore contacting the larger axial bore.

Inventors: KAPLAN ALAN S, MASKREY ALFRED E, MATTEO AUGUSTINO JR, ROBERTSON SAMUEL E, KAPLAN, ALAN, S., MASKREY, ALFRED, E., MATTEO, AUGUSTINO, JR., ROBERTSON, SAMUEL, E.
Applicants: EMKAY MFG CO, EMKAY MANUFACTURING COMPANY
Application year: 1988
Main classification: B05D5
IPC codes: C23C14, C30B33, H01L21