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Tape automated bonding (TAB) is a suitable technology for assembling ICs with a high number of l/Os. The gang bonding process usually applied requires increasing thermode forces for chips with high lead counts and narrow tolerances regarding thermode parallelism and planarity. Due to the high bonding pressure, TC bonding of Au bumps to Au‐plated tapes becomes critical for these applications. In order to avoid damage to the pad structure an inner lead bonding (ILB) process with reduced pressure is required. A tape metallisation of 0.5–1.0 µm Sn is not sufficient for a significant reduction of thermode pressure. As an alternative, the application of an eutectic Au‐Sn cushion which is deposited on top of the bumps is presented. A modified bumping process was developed for the deposition of the solder bumps. Soldering of the Au‐Sn bumps to a Au‐plated tape was performed successfully by two techniques: thermode gang bonding and laser soldering. Bond parameters and tin layer thickness were optimised. Reliability investigations by thermal ageing were performed. The special metallurgical aspects of the system were investigated with a microprobe.

Au/In isothermal solidification technique was evaluated as an alternative method for high performance die attachment. Bonding could be achieved at temperatures between 250°C ‐ 3008C for about five to ten seconds. The microstructures of the bonds were studied and their effects on the reliability analysed. The quality of the bonds depends very much on the surface waviness of the substrate. For high quality substrates, bonding was successfully achieved on 3mm × 3mm dies, which is almost one order of magnitude bigger than the die size achievable for Au/Si eutectic bonding, and the bonds show no obvious degradation after 2,800 cycles between –55°C to 125°C.

As the hybrid market changes, many hybrid companies are being forced to adjust to reduced defence budgets and to the encroachment of epoxy board based SMT on traditional hybrid areas. This paper considers the establishment of an intelligent power module technology as a viable way to utilise the strengths of hybrid technology, in a field where there is an expanding market and, at present, not too much competition. The basic techniques are described, some of the potential pitfalls are highlighted, and the likely scale of technical and personnel investment is indicated.

Acquisitions. DEK—UIC DEK Printing Machines Limited (DEK) have announced that negotiations have been concluded with Dover Corporation, New York, to acquire the majority of the share capital of DEK. The object of this exercise is to enable DEK and Universal Instruments Corporation (UIC) who are part of the Dover Corporation, to amalgamate and thus further advance their plans to offer a fully integrated package of equipment for the automated hybrid factory.

The reliability of chip‐on‐film (COF) packages is fundamentally dependent upon the quality of the eutectic Au‐Sn joint formed between the Au bumps on the integrated circuit (IC) device and the Sn‐plated Cu inner leads. Therefore, it is essential that an appropriate bonding temperature is achieved during the inner lead bonding (ILB) process. The purpose of this paper is to identify the optimal processing conditions which maximize the reliability of the Au‐Sn joints.

The paper commences by performing an experimental investigation to establish the temperature at three specific locations within the COF/ILB system in a typical gang‐bonding process. The relationship between the setting temperature of the bonding tool and the temperature of the tool surface is then calibrated using an off‐line experimental system. An ANSYS finite element (FE) model is then constructed to simulate the temperature distribution within the COF/ILB system under representative temperature conditions. The validity of the numerical model is confirmed by comparing the simulation results with the experimental temperature measurements. The FE model is then used in a 2³ factorial design process to evaluate the effect of the principal COF/ILB processing parameters, namely the contact area, the tool temperature and the stage temperature, on the temperature induced at the interface between the Au bumps on the IC chip and the Sn‐coated Cu leads on the polyimide film.

The results reveal that the interfacial bonding temperature is determined primarily by the stage temperature.

A regression analysis model is applied to the factorial design results to construct a COF/ILB design chart which enables the rapid identification of the stage and tool temperatures required to achieve the minimum feasible eutectic bonding temperature.

Direct copper bonded (DCB) alumina substrates are among sophisticated technical materials suitable for application in electronics, automotive and engineering industries. DCB substrates resist very severe operational conditions and assure high reliability. This technology provides alumina substrates which are very strongly bonded to copper foil, due to the solidified eutectic alloy Cu2O‐Al2O3 or a suitable vitreous solder. Such substrates are ideal for the construction of elements in microelectronics hybrid circuits, power circuits and devices. As the bonding layer of a solidified eutectic or vitreous solder is very thin, the thermal resistivity stays sufficiently low; in addition, the dilatation properties of DCB substrates are close to those of silicon. This enables soldering of large silicon chips without the risk of creating mechanical stress and allows for the production of devices with very high construction effectivity. Examples of such applications are potential‐free modules, bridge circuits, automotive ignition modules and Peltier elements. The vitreous bonding layers are advantageous for certain applications. State‐of‐the‐art DCB bonding technology was developed for DCB aluminium nitride substrates, which have even better thermal qualities.

The purpose of this paper is to characterize pressure non‐uniformity in a wafer‐to‐wafer bond chamber using pressure sensitive paper.

Pressure non‐uniformity in a wafer‐to‐wafer bond chamber is characterized using pressure sensitive paper. The effect of poor pressure uniformity is discussed, and the non‐uniformity corrected for use in a eutectic Au/Sn based wafer‐to‐wafer bond.

Several types of under solder metallization were also investigated, with Nb/Au seed metal providing the best overall result with good solder compression, liquid proof seal and minimal solder spill‐out. Solder compression versus pressure applied was studied to achieve an excellent gap control (2‐3 μm) between the bonded substrates.

This paper shows that characterization of applied pressure measured directly at the substrate is an important aspect in the development of high yielding bond processes.