Hot gas micro-bonder

Vacuum news aluminium borosilicatc. The glass is formed by drawing into sheets and then cut into finished pieces. A typical smoothness is less than micro-inch. A publication giving comprehensive details on chemical constituents and properties is available from Electrosil Limited. Electrosil Limited, UK Circle number 62 on Reader Enquiry Service card New Instrumentation from Sloan Sloan Instruments Corporation have announced that their deposit thickness monitor, Model DTM-2A, has been superseded by Model DTM-3. The two models are exactly the same except that the D T M 3 has an extra 100-kc range which has been added for convenience for " t h i c k " film deposition. The D T M now has ranges of 1, 3, 10, 30 and 100 kc at no additional cost. The addition of the 3-kc range is said to make the D T M more convenient for use in optical applications where the deposition of ¼ wavelengths of magnesium fluoride and cadmium sulphide require a frequency setting of 1.5 kc. Previously optical users had to use the 10-kc range or use a 50 per cent shield to get them on the l-kc scale. The addition of the 100-kc range extends the range of the instrument for single depositions 3.3 times over the previous 30 kc, thus providing greater applicability for long a n d / o r thick deposition. The Corporation have also announced the O M N I - I , a complete system used for the automatic control of thickness and rate of thinfilm vacuum deposition. Two O M N I - I ' s can be slaved together to yield an infinite variety of alloy or compound compositions from multiple evaporation sources. Heretofore, thin-film workers used a deposit thickness monitor (DTM) and deposit rate control (DRC) to achieve full system contlol. The OMNI-1 is a single unit with all of the features of the D T M and D R C plus the following advantages: (1) A dual high-low set point meter has been added to the thickness monitoring section. The low set point appropriately opens the substrate shutter once the source is under rate control and the high set point closes the shutter once the appropriate thickness has been reached. (2) Automatic re-zeroing has been added. When desired, the instrument now re-zeros itself automatically after every deposition. Sloau l~strumems Corporation, California, USA Circle number 63 on Reader Enquiry Service card Hot gas micro-bonder The hot gas micro-bonder type B400, recently introduced by G V Planer Limited, utilizes a fine high-temperature gas jet to effect bonding, in particular, hot-gas soldering of micro-joints, and the like. I m p o r t a n t uses of the equipment are said to include the facebonding of semiconductor chips to metallic thin-film areas in micro-circuits, attachment of leads in electronic-component manufacture and solder bonding of wires to film-circuit patterns or semiconductor devices.

B400 hot gas micro-bonder in use

The gas stream, e,g. nitrogen or a nitrogen - hydrogen mixture, is heated electrically at a thermostatically controlled temperature of up to 400 °C and the applications of the jet can be controlled at preset durations of up to 15 seconds. The flow-rate of the gas is controlled by means of a pressure regulator and gauge. Jet diameters ranging from 0.01 to 0.10 inch can be obtained by using interchangeable nozzles. Provision is made in the case of the larger diameter nozzles for use of a centrally located projecting pin to retain the component to be joined during the bonding operation, where required. A thermostatically controlled, heated sub-stage with micromanipulator position control is used to support the components to be bonded. A vacuum facility in the sub-stage serves to retain the component during operation, and a vacuum tweezer is provided for the handling of small pieces. A binocular microscope is included in the equipment together with means of variable intensity illumination. G VPlaner Limited, UK Circle number 64 on Reader Enquiry Service card Line trap with built-in valve The Vacuum Division of Varian Associates has introduced a roughing line trap with a built-in valve. This new unit is claimed to speed up rough pumping operations by capturing water vapour and to improve the cleanhness of a vacuum system by trapping backstreaming oil. A vacuum system can also be evacuated to the 10 -s torr region and held at that pressure by just a two-stage mechanical

Varian trap valves:left, cryotrap valve; right, molecular-sieve trap valve pump and this trap valve. Installation is simplified with two standard 2t-inch outer diameter ConFlat flanges that mate with matching flanges. Varian is offering two types of trap valves. The molecular-sieve trap valve uses 500 g of zeolite material for trapping action. The cryotrap valve uses 1 litre of liquid-mtrogen to provide almost unlirmted trapping capacity. Models of both types are available with integral heaters for either 110 or 220 V operation. Varian Associates, Vacuum Division, California, USA Circle number 65 on Reader Enquiry Service card Cryosorb cold traps Vacuum physicists and cryogenic engineers at Granville-Phillips have carefully designed a cryogenically cooled adsorption or condensation cold trap that permits the use of diffusion pumps even in the most critical operations. These traps are said to effectively prevent oil and oil vapours from creeping or diffusing hack into a properly operated system for extended periods of time. The manufacturers recommend Cryosorb traps for use as an economical method for trapping high-vacuum systems. When supplied with metal-to-metal flanges the traps are bakeable to 450 °C and are useful in ultra-high-vacuum and ultra-clean systems. Due to their all-stainless-steel construction, Cryosorh cold traps are said to be especially useful on mercury pumped systems. 91