Etched metal foil screens have been developed by ERA which are capable of 50um features (lines and spaces). Standard thick film printing equipment and pastes may be used, but optimum registration and resolution will be achieved in combination with associated advanced printer and paste respectively.
Advanced techniques have been developed by Heraeus, for the production of sub-micron particle size, high performance thick film fine line printing pastes. A paste based on these methods, in a rheology optimised for the etched foil screen has been developed, and printability, bondability and adhesion life testing completed.
Advanced printer design by EKRA, has made available print-to-print and layer-to-layer registration within +/- 15um. This has been achieved by the addition of a high resolution optical alignment system to a highly stable machine base.
These developments were brought together in the fabrication by Dassault and Sorep of two multilayer (5 and 6 conductor layer respectively) MCM circuits. Some of the prints contained in excess of 10 metres of tracking at dimensions down to 50 um line and space. Continuity, isolation, wire bonding and adhesion testing were all successful.
The electronics industry is now looking towards pushing thick film processing towards much higher interconnect densities for technologies such as multichip modules(MCMs). The establishment of a manufacturing technology for high density thick film printing will enable much lower cost production technique for electronic packaging and therefore provide a significant competitive advantage for the users thereof. This approach has the particular advantage that it does not demand a major departure from established screen printing technology.
It is the objective of this proposal to realise a thick film process for production of dense 25µm lines with a 25µm line spacing over an area of 150x150mm for up to six conductor layers for MCMs providing an increase of 10 to 100 times in circuit densities currently achievable using thick film technology. This technical objective will be realised through the following principle tasks:
- sub-micron particle size thick film conductor paste development
- advanced print screen design and fabrication
- development of a high accuracy thick film screen printing machine
- demonstration of the technology in an advanced data processing and in a representative telecommunications MCM application.
The proposal consortium (which includes three SMEs)comprises experts in all the required technical areas including thick film paste manufacture, fine-line screen printing design and fabrication, multilayer hybrid electronics production(x2)and screen printer manufacture. The project will result in an established route for exploitation of this advanced, low cost interconnect technology in Europe. The first applications of this technology will be in MCMs. The total world market for MCMs in 1994 is projected to be 0.7 billion ECU per annum. This development will address 75% of this market alone.
Funding SchemeCSC - Cost-sharing contracts
KT22 7SA Leatherhead