PRESSURE WELDING BONDING APPARATUS

Abstract: The bonding apparatus comprises a substance to be bonded-holding means (3), a pressing means (4) for pressure welding substances (2) to be bonded to each other, and a superhigh vacuum bonding chamber (1) provided with said holding means (3) and said pressing means (4). A superhigh vacuum bonding preparatory chamber (6) is connected with said superhigh vacuum bonding chamber (1) through a gate valve (7) and a substance to be bonded-conveying means (10) is arranged for conveying the substances (2) to be bonded between said superhigh vacuum bonding preparatory chamber (6) and said superhigh vacuum bonding chamber (1). The preparatory chamber (6) is provided with a rotary preparatory table (23) having a plurality of stages (8) for releasably supporting holders (14) for substances (2) to be bonded, the preparatory table (23) being arranged to position successive stages (8) in register with the conveyor (10).

Description: The present invention relates to the bonding of metals or ceramics among themselves or ceramics to metals and the like, and in particular to a bonding apparatus suitable for the bonding of parts of precision machines. It has been known that the pressure welding of for example metals among themselves is possible by approaching surfaces to be pressure welded to the distance from each other, at which an inter-atomic gravity force can act. However, since usually a surface coat such as oxidized coat and nitrified coat exists on a metal surface, it is difficult to pressure weld metals among themselves. Thus, a method, in which surfaces to be pressure welded are held at high temperatures and the diffusion bonding of materials having a surface coat without containing strong chemical bonds therein is carried out by utilizing the diffusion phenomenon of said surfaces to be pressure welded has been proposed for the general pressure welding method. This method shows a defect in that since the materials to be pressure welded are heated to temperatures near the recrystallization temperatures thereof, metallographical change and thermal strain are produced in the portion bonded and as a result, it is unsuitable for the bonding of parts of precision machines requiring high accuracy. On the other hand, a method has been proposed in which the surface coat layer is removed by the friction of surfaces to be pressure welded or by brushing the surfaces to be pressure welded with a metal brush in place of a heating treatment of the surfaces and the pressure welding at high temperatures is speedily carried out before the surface coat has again formed. However, also this method has shown a defect in that since much strain and heat are induced on the surface to be pressure welded, the dimensional change of the portion pressure welded in inevitable. As described above, the pressure welding is remarkably dependent upon the surface state of metals, so that is is almost impossible in the even that the surface coat layer exists. Accordingly, the pressure welding is possible if a clean surface, on which the surface coat layer does not exist, can be obtained. It is, however, remarkably difficult to remove a surface coat without giving any strain to the surface, and it is difficult to remove the surface coat layer to make very remarkably small surface strain. One of the present inventors found from his various investigations that metals can be readily bonded among themselves without showing any metallographical change or thermal strain of the material pressure welded, or any dimensional change of the portion pressure welded, and without requiring any special means such as heating treatment, by pressure welding them under superhigh vacuum of 10⁻⁹ mmHg or more, after removing a metal surface coat by spattering with inert gas ions (Japanese Patent Application No. 53-32416). However, since a bonding chamber must be returned to an almost atmospheric pressure condition when the substances to the bonded are put in or removed from the bonding chamber, it takes considerable time to return the inside of the bonding chamber to 10⁻⁹ mmHg or more when the substances are to be bonded. Accordingly, an improvement of productivity cannot be expected. It is an object of the present invention to eliminate the above described defects and to provide an apparatus for bonding metals or ceramics among themselves or ceramics to metals and the like more effectively within a superhigh vacuum bonding chamber. According to the invention a bonding apparatus comprising a substance to be bonded-holding means, a pressing means for pressure welding substances to be bonded to each other, is characterised by a superhigh vacuum bonding chamber provided with said holding means and said pressing means, a superhigh vacuum bonding preparatory chamber connected with said superhigh vacuum bonding chamber through a gate valve and a substance to be bonded-conveying means for conveying the substances to be bonded between said superhigh vacuum bonding preparatory chamber and said superhigh vacuum bonding chamber. The invention will now be described, by way of example with reference to the accompanying partly diagrammatic drawings, in which:- Figure 1 is a plan view of an embodiment of the invention; Figure 2 is a side view of the apparatus of Figure 1 as viewed from the direction A-A thereof; Figure 3 is a diagram showing a superhigh vacuum evacuating apparatus used in an embodiment of the present invention; and Figure 4 is a fragmented perspective view of the principal parts explaining the operation of an embodiment of the present invention. The present embodiment is mainly composed of the following four portions: The first portion is a superhigh vacuum bonding chamber (hereinafter referred to simply as a bonding chamber) 1. The bonding chamber 1 is held under superhigh vacuum of 10⁻⁹ mmHg or more and provided with a holding means 3 for fixedly holding two substances 2 to be bonded, a pressing means 4 for generating a minute pressure, a differential pressure type spatter-etching means 5 capable of spatter-etching surfaces to be bonded with inert gas with holding the vacuum of 10⁻⁹ mmHg in order to make the surfaces to be bonded clean surfaces, and substantially ideal ones, prior to the bonding operation. The second portion is a superhigh vacuum preparatory chamber (hereinafter referred to simply as a preparatory chamber) 6. The preparatory chamber 6 is held under high vacuum of 10⁻⁸ mmHg or more and cut off from the bonding chamber 1 by a gate valve 7. The preparatory chamber 6 communicates with an atmosphere when the substance 2 to be bonded is put in or removed but can be held under superhigh vacuum after the substance 2 to be bonded has been mounted on a plurality of holders 8. In addition, the preparatory chamber 6 is provided with a spatter-vapour coating apparatus 9 capable of coating a thin film of other substances on the surface of the substance 2 to be bonded. The third portion is a conveying means 10 for conveying the substance 2 to be bonded from the preparatory chamber 6 and mounting it on the holding means 3 of the bonding chamber 1. The forth portion is a superhigh vacuum evacuating apparatus 11 for producing a superhigh vacuum atmosphere within the preparatory chamber 6 and the bonding chamber 1, as shown in Figure 3. These portions will now be described in more detail. The bonding chamber 1 is generally cylindrical in shape and is provided with a rotary table 12 therein which is controlled so as to be rotatable through suitable angles by a rotary apparatus 17 arranged outside the bonding chamber 1, if need arises. This rotary table 12 is provided with a substance to be bonded stage 13 having an upwardly facing channel-shaped section fixedly mounted thereon as shown in Figure 4. The holding means 3 of the substance 2 to be bonded is constructed to hold the substance 2 within the bonding chamber 1 by engaging a collar member 14a of a substance holder 14 with a groove 13a in stage 13. In addition, the bonding chamber 1 is provided in the upper portion thereof with a second substance to be bonded stage 15 composing a part of the holding means 3 facing the stage 13. The stage 15 has an inverted channel shape section, which is opposed to that of the lower stage 13, and is provided with a groove 15a so as to hold a substance to be bonded holder 14 in the reverse direction. This substance to be bonded stage 15 is connected with the pressing means 4, and is movable up and down, and is provided with a closing apparatus 16 for opening and closing the arms of the channel section stage 15. Also, the bonding chamber 1 is provided with the differential pressure type etching means 5 for etching the surface of the substance to be bonded 2 if need arises. Of said differential pressure type etching means 5, an upper spatter-etching apparatus 5a is provided in the upper portion of the bonding chamber 1 at a side opposite to said second substance to be bonded stage 15 while a lower spatter-etching apparatus 5b is provided in the lower portion of the bonding chamber 1 facing to the second substance to be bonded stage 15. In addition, the bonding chamber 1 is provided with an exhaust port 18 connected with said superhigh vacuum evacuating apparatus 11, operation-monitoring ports 19,20, an instrument port 21, a surface analysis port 22 and the like. The cylindrical preparatory chamber 6 is provided with a rotary table 23, which is similar to the rotary table 12 provided in the bonding chamber 1, four holders 8 being fixedly mounted on the rotary table 23 at regular intervals of 90°. These holders 8 have a channel-shaped section, which is generally the same as that of said substance to be bonded stage 13, as shown in Figure 4. The holders 8 are fixedly mounted so that the open side of the channel-shape is directed sidewards, and the substance to be bonded 2 is held by engaging the collar member 14a of a substance to be bonded holder 14 with a groove 8a of the holder 8. The preparatory chamber 6 is provided with the spatter-vapour coating apparatus 9 on the side thereof facing to the holders 8, as the table 23 is turned, whereby a thin film of other substances can be coated on the surface of the substances 2 to be bonded mounted on a holder 8. The substance to be bonded-conveying means 10 is provided with a movable shaft 10a which is rotatable and movable in an axial direction, said movable shaft 10a passing through the side wall of the preparatory chamber 6 and extendable as far as the substance to be bonded stage 13 in the bonding chamber 1 through said holder 8 and said gate valve 7. This movable shaft 10a is provided with a screw member 10b at the forward end thereof, the substance 2 to be bonded being conveyed between the preparatory chamber 6 and the bonding chamber 1 by screwing this screw member 10b in a complimentary screw member 14b of the substance to be bonded holder 14. Furthermore, an exhaust port 24 is connected with the superhigh vacuum evacuating apparatus 11. The superhigh vacuum evacuating apparatus 11, as shown in Figure 3, comprises superhigh vacuum pumps P₁,P₂ capable of obtaining a vacuum of about 10⁻² to 10⁻¹⁰ mmHg, a high vacuum pump P₃ capable of obtaining a vacuum of about 10⁻⁴ mmHg, vacuum gauges G₁,G₂, valves B₁,B₂,B₃,B₄,B₅,B₆,B₇, B₈ arranged between the pumps P₁,P₂,P₃, the bonding chamber 1, the preparatory chamber 6 and an argon gas bomb 25, the inside of the bonding chamber 1 and the preparatory chamber 6 being adjusted to the desired vacuum and simultaneously the bonding chamber 1 and the preparatory chamber 6 being fed with argon gas used for ion-etching or ion-spatter vapour coating by appropriate opening and closing the various valves. The operation of apparatus according to the present embodiment will now be described. At first, a superhigh vacuum atmosphere is produced in the bonding chamber 1 and the preparatory chamber 6. Then the preparatory chamber 6 is opened to atmospheric pressure and a plurality of substance to be bonded holders 14, on which the substance 2 to be bonded is mounted, are mounted on respective holders 8. After a plurality of substance to be bonded 2 are fixedly mounted on the holder 8, the desired superhigh vacuum is again produced in the preparatory chamber 6. The surface of the substance 2 to be bonded put in the superhigh vacuum preparatory chamber 6 can be subjected to the spatter-vapour coating if need arises. In this case, an inert gas such as argon gas is introduced into the preparatory chamber 6 under the vacuum of about 10⁻⁵ mmHg and a substance for the desired thin film can be coated on the surface to be spatter-bonded as a spatter-vapour coated film by use of this invert gas. After the spatter-vapour coated film is coated, a high vacuum of 10⁻⁸ mmHg is again produced within the preparatory chamber 6. Upon completion of the operation in the preparatory chamber 6, the screw member 10b is screwed in the screw member 14b of a substance to be bonded holder 14 by rotating the movable shaft 10a and the substance to be bonded holder 14 is removed from the holder 8 by axially moving the movable shaft 10a. Then the substance to be bonded holder 14 is fixedly engaged with the substance to be bonded stage 13 in the bonding chamber 1 by rotating the rotary table 23 in the preparatory chamber 6 by 45°, rotating the movable shaft 10a by 90°, and simultaneously opening the gate valve 7 to pass the holder 14 through the gate valve 7 and engage the holder 14 in the stage 13. After the substance to be bonded holder 14 is fixed, the movable shaft 10a is rotated in the reverse direction to remove from the substance to be bonded holder 14 and return to the original position in the preparatory chamber 6. Next, the rotary table 23 is further rotated by 45° to screw the pointed end of the movable shaft 10a in another substance to be bonded holder 14, the movable shaft 10a being axially moved to remove the substance to be bonded holder 14 from the holder 8, and the movable shaft 10a being rotated by 90°. At this juncture, in the bonding chamber 1, the rotary stage 12 is under the condition that it is rotated by 180° and the substance to be bonded stage 15 is under the condition that it is lowered in to a fixed position aligned in the path of the shaft 10a. Subsequently, the movable shaft 10a is axially moved to fixedly engage the substance to be bonded holder 14 with the substance to be bonded stage 15, the movable shaft 10a being rotated to remove from the holder 14, the movable shaft 10a being returned to the original position in the preparatory chamber 6, and simultaneously the gate valve 7 being closed. Under this condition, one of the substances 2 to be bonded fixedly held in the bonding chamber 1 is mounted on the pointed end portion of the pressing means 4 and the other one is mounted on the rotary stage 12. Accordingly, the surfaces of the substances 2 to be bonded are fixed at the position facing to the upper and lower differential pressure type spatter-etching apparatus 5a,5b, respectively, so that the surfaces of the substances 2 to be bonded are subjected to the spatter-etching until the clean surface, which is substantially an ideal one, is obtained. Such a spatter-etching apparatus 5a,5b on the market can carry out the spatter-etching by use of an inert gas under a superhigh vacuum of 10⁻⁹ mmHg and can spatter-etch an area of a certain extent or more by the surface-scanning. The substances 2 to be bonded, to which the substantially ideal clean surfaces were given, are positioned face to face with each other by rotating the rotary stage 12 by 180°. Under this condition, minute pressure is added to both surfaces to be bonded by means of the pressing means 4 to carry out the bonding operation. After the completion of the bonding operation, the gate valve 7 between the bonding chamber 1 and the preparatory chamber 6 is opened and the movable shaft 10a is inserted and screwed in the holder 14 whilst removing the pressure from the pressing means 4. Then both arms of the substance to be bonded stage 15 are opened by means of the closing apparatus 16 to loosen the engagement of the substance to be bonded holder 14 with the substance to be bonded stage 15, the movable shaft 10a being returned into the preparatory chamber 6, the substance to be bonded holder 14 being engaged with the holder 8 in the preparatory chamber 6, and simultaneously the gate valve 7 being closed. Thus, both of two substances bonded are brought into the preparatory chamber 6 in bonded condition and then can be taken out of it by returning the pressure inside the preparatory chamber 6 to an atmospheric pressure. Thus the procedure from the installation of the substance to be bonded in the bonding chamber to its removal from the bonding chamber is over. A large number of bonded products can be obtained by repeating the above described procedure. Although the preparatory chamber 6 disclosed is provided with four holders 8 therein, so that two bonding operations can be carried out without returning the pressure inside the preparatory chamber 6 to an atmospheric pressure, it goes without saying that a larger number of bonding operations can be continuously carried out by increasing the number of the folder 8 in the preparatory chamber 6. As described above, according to the present invention, a bonding chamber can be always held under superhigh vacuum and the inside of the bonding chamber can be always kept clean, so that not only the inside of the bonding chamber can be free from stains in the open air but also the time required for producing a superhigh vacuum atmosphere can be shortened thereby effectively carrying out a superhigh vacuum bonding process.

Claims: 1. A bonding apparatus comprising a substance to be bonded-holding means (3), a pressing means (4) for pressure welding substances (2) to be bonded to each other, characterised by a superhigh vacuum bonding chamber (1) provided with said holding means (3) and said pressing means (4), a superhigh vacuum bonding preparatory chamber (6) connected with said superhigh vacuum bonding chamber (1) through a gate valve (7) and a substance to be bonded-conveying means (10) for conveying the substances (2) to be bonded between said superhigh vacuum bonding preparatory chamber (6) and said superhigh vacuum bonding chamber (1). 2. Apparatus as claimed in claim 1, characterised in that said holding means (3) comprises a first stage (14) for releasably supporting a holder (14) for a substance (2) to be bonded, said first stage being mounted on a rotatable table (12), and a second stage (15) for releasably supporting a holder (14) for a substance (2) to be bonded, said second stage (14) being reciprocably supported for movement towards and away from the table (12). 3. Apparatus as claimed in claim 1 or claim 2, characterised in that the preparatory chamber is provided with a rotary preparatory table (23) having a plurality of stages (8) for releasably supporting holders (14) for substances (2) to be bonded, the preparatory table (23) being arranged to position successive stages (8) in register with the conveyor (10). 4. Apparatus as claimed in claim 2 or 3, characterised in that the conveyor comprises a rod (10) having a threaded end (10a) adapted to engage a threaded bore in a holder (14), the rod being axially traversable between the bonding chamber (1) and preparatory chamber (6), and rotatable. 5. Apparatus as claimed in claim 4, characterised in that the stages (13,15,8) in the bonding and preparatory chambers (1,6) are of channel form having internal grooves (13a,15a,8a) at opposite sides for engaging flanges on a substance holder (14), the second stage (15) of the bonding chamber (1) being operable for release of a holder (14) by movement apart of the sides of the channel shape.

Inventors: FUNAKUBO, HIROYASU, KOMURA, OSAMU, SAKANOUE, HITOYUKI, SEKIGUCHI, YUKIO
Applicants: FUNAKUBO, HIROYASU, LIFE TECHNOLOGY RESEARCH FOUNDATION, SUMITOMO ELECTRIC INDUSTRIES LIMITED
Application year: 1985
Main classification: B23K20
IPC codes: C04B37, B23K20