FUNDING FLIPS AND BUMPS

Industry and academics are working on projects to increase competitiveness of chip assembly. By Arlene Foster

In the publicity surrounding the multi-million pound Government-backed inward investments in the UK electronics sector, projects arising from the thinner wedges of the Government cash pie have been overshadowed.

While the big investments have secured a top position for the UK in semiconductor and electronics manufacturing, more modest investments are working at adding value to basic assembly or silicon chip manufacture.

One such initiative was recently launched and part-funded by the Engineering Physical Sciences Research Council (EPSRC). Working with industrial and academic partners, it is providing £1m of funding for two projects which seek to increase the competitiveness of the UK in the core area of chip assembly.

David Topham, who coordinates the Electronic Product Design and Manufacture initiative on behalf of the EPSRC, explains: `The future health of the UK electronics industry lies in having the skill and resources to use silicon, not just to make it.’

The first project seeks to develop a low-cost means of directly attaching `naked’ silicon chips, reliably and in volume, to printed circuit boards. As electronic equipment manufacturers have increased processing speeds, so the packages which contain each silicon device have become smaller.

This has partly met a drive towards miniaturisation in electronic goods but is also because the bigger the package the greater the interference with electronic signals in the device. The most effective solution in meeting manufacturers’ demands for the smallest package with the best signal propagation features is the flip chip. Used for many years in military applications, flip chips are unpackaged silicon dies. Solder is directly applied to connection areas on the chip, which is then flipped over on to the PCB or substrate and connected down.

The three-year project aims to find low-cost ways of achieving high-volume production of micron-scale solder joints. Project partners claim a successful outcome would enable flip chip technology to be applied for the first time to volume production consumer electronic goods, giving the UK electronics manufacturing industry a lead over US and Far Eastern rivals.

The project will use the latest printing techniques to produce micron-scale bumps on the surface of the silicon. The silicon will then be flipped over to align face down with geometrically mirrored contact areas similarly produced on the PCB.

Significant commercial benefits will fall to the the industrial partners. These comprise contract electronics manufacturer D2D (formerly ICL’s manufacturing arm), GEC Plessey Semiconductors, aerospace manufacturer Matra-BAe Dynamics, printing equipment supplier DEK and solder manufacturer Multicore Solders.

Research and academic input is being provided by Salford and Loughborough universities. Both have carried out feasibility studies for the project: Salford has researched production enhancement systems in micro-electronic assembly for some of the industrial partners.

Salford will use its expertise in soldering of surface mount devices to find new ways of attaching the silicon to the PCB, while Loughborough will decide on the material to be used to form the bumps on the silicon.

D2D has spent £1m on clean room technology for the project while GEC Plessey and Matra-BAe Dynamics will contribute their considerable expertise in chip manufacture and electronics. They will also provide new chip designs and use of their testing laboratories. DEK will produce the machinery to print down the connection points, with solder provided by Multicore.

While the industrial partners will be first to reap the commercial benefits, EPSRC funding rules mean the technology and associated process developments arising from the collaboration will be passed on to the rest of the UK’s PCB manufacturers. This will be done by disseminating the results through seminars and journals.

For the universities, the project offers opportunities to develop continuing work and real collaboration with industry. `We’ve learned through previous ventures with industry that it is important to collaborate on challenges as they happen,’ says Ndy Ekere, of the manufacturing systems department at Salford University.

Spin-offs in new research are expected to flow from the project, which presents a considerable challenge for the university teams, adds Topham. `A lot of underlying science will come out of the project, which will benefit UK science and electrical engineering.’

The second three-year project focuses on improving the design for manufacture process in the PCB sector. With reduced time-to-market periods, pressure for reduced costs and ever changing, higher quality products, improving this process is regarded as critical in determining the profitability of PCB manufacturers.

Again D2D and Salford university are collaborating, with CAD supplier Zuken-Redac Systems. The project has the support of industry bodies including the Printed Circuit Interconnection Federation. Through such bodies the project team will be able to trawl the range of companies involved in PCB manufacture.

The project aims to develop a multi-media design advice system which will act as a harvester of information from all the parties concerned in the design for manufacture process. The system will be linked to CAD tools, which will automatically match designs against new developments and tightening constraints arising in this market.

Therese Lawlor-Wright, leading the project for Salford University, explains: `Electronic product designers sit at CAD workstations and drive factories they’ve never seen. With 80% of manufacturing costs incurred at the design stage, this can result in costly misunderstandings between the two. We’re trying to build a prototype system that will close this loop by bringing information back from the manufacturer to influence the designer.’ The project team hope to build a `virtuous circle’ between the designer and the manufacturer which should result in reduced manufacturing costs, higher quality boards and greater partnership.

As the UK electronics industry matures, projects such as the EPDM initiative may play an increasingly important role in securing a competitive edge for Britain in global electronics markets. But Government funding for EPDM at £3.5m represents a tiny part of the total EPSRC grant budget of £600m. A greater funding effort will be needed, says Topham. `We need to be spending as much on the use of chips as we do on making them. In terms of public spending, the balance between the two has yet to be struck.’