Patent GB-995853-A (GB)
Title: Apparatus for bonding wire-like elements to articles
IPC: G05G5/04
Filed: 1961-09-27
Abstract: 995,853. Welding by pressure. WESTERN ELECTRIC CO. Inc. Sept. 27, 1961 [Oct. 6, 1960], No. 34662/61. Heading B3R. [Also in Division H1] An apparatus for bonding a wire-like element between two regions of an article such as a transistor has a tool which both feeds the element from a supply and acts as a bonding tool, the apparatus having means for positioning the tool in its bonding position over the first region of the article and for subsequently moving it through a predetermined distance to its bonding position over the second region. The manually-operated apparatus described has two units 10 and 11 for bonding wires respectively from terminals 13<SP>1</SP> and 13 on the header 15 of a semi-conductor device to the corresponding alloyed metal strips 14<SP>1</SP> and 14 on the semi-conductive wafer. Several headers are placed in a jig 20 sliding on the heater 17 used for the thermo-compression bonding, the jig being indexed so that the header to be worked on is centred under the lens 19 of a comparator 24. The heater is itself mounted on a table 18 which is movable in any direction in the horizontal plane so that the header may be correctly orientated, using the comparator, for bonding operations. Operation of the similar bonding units 10, 11 is identical, but one unit, e.g. unit 10, is put completely through its cycle before the other. Unit 10 consists of a hollow bonding tool 40 mounted with a wire supply reel 36 at the end of a weighted arm whose pivot point is mounted on a sliding block 26. Initially, the unit is retracted, as shown in Fig. 1, but after desired orientation of the header the unit 10 is pushed forward until its set screw 28 meets the flat face of a cam 50 (set at 180 degrees from the position shown in Fig. 3) which is mounted on the base of the apparatus. The bonding tool is now directly over the terminal 13<SP>1</SP> on the header (Fig. 6). A single movement of the cam lever 46 between its stops 49<SP>1</SP> and 49 first allows the weighted arm 33 to drop, bringing the bonding tool into contact with the terminal post on the heated header and then, a bond having been formed, returns the arm to its raised position. Rotation of cam 50 (to the position shown in Fig. 3) now retracts the bonding unit through the predetermined distance necessary to bring the bonding tool over the alloyed strips on the wafer. Cam lever 46 is rotated back to its stop 49<SP>1</SP> again causing the tool to descend, bond, and rise, so that the wire 12<SP>1</SP> is now joined between the terminal and the alloy stripe. Next, the unit 10 is fully retracted. During this stage a lever 60 attached to the unit is depressed against the supply reel 36, preventing the reel from rotating and so breaking the wire at its weakest point, adjacent the bond on the alloyed stripe (Fig. 12). The broken end of the wire issuing from the tool is reformed about the cylinder 43 on the tip of the tool by contact with a cross-piece 64, and is ready for subsequent bonding operations. The other unit, 11, is now operated to connect terminal 13 to stripe 14, and the process repeated on the other headers. It is pointed out that although a manually-operated apparatus is described the apparatus readily lends itself to complete mechanization.