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Use of Additive Conductive Materials to reduce cost and Environment al Impact of Printed Circuit Board Manufacture

Objective


The objective of the ACME project was to develop new technology for PCB manufacture that would have the following advantages:

Reduced cost (through use of simpler/more automated processes and cheaper base materials).

Reduced environmental impact (through the reduction or elimination of toxic pollutants and waste from PCB manufacturing processes).

The project used the principle of "additive" technology to achieve the objectives; this involved the building up of conductive and dielectric layers to form multilayer circuits, thus eliminating the need for complex and environmentally damaging "subtractive" technologies that are currently used.

Two distinct (though inter-related) technologies were involved. For each technology, materials and processing techniques were developed; then test vehicles and demonstrator circuits were built and evaluated:

UV Screen technology - Circuitry with a resolution of around 200 micron track/gap by screen printing and UV curing the conductive and dielectric layers.

Photoimaged technology - Circuitry with a resolution of around 150 micron track/gap by photo-defining a circuit pattern in the dielectric, and then filling this pattern with conductive material.

Cost reduction achievements - The projected cost benefits of ACME have been reduced by the efficiency improvements by most PCB manufacturers during the lifetime of the project; nevertheless, cost savings of 10-20% for the UV and 20-30% for the Photo defined process are possible in many of the target applications that have been identified for exploitation of the ACME technologies.

Environmental achievements - This project has shown that ACME can reduce heavy metal waste by 100%, wastewater by 75% and energy use by 50%. The use of formaldehyde plating baths, and acid or ammoniacal etchants can be eliminated, and the possibility of using recyclable base materials is opened up.
The objectives of this project are to reduce the cost and
environmental impact of present Printed Circuit Board manufacture; this will be achieved by replacement of the current "substrative" technique (forming conduclive tracks by etching away typically 80% of the surface of copper clad panels) with new "additive" technology (i.e. building up of circuitry on base materials layer by layer). The potential benefits to Europe are: Cost Reduction.

Process steps reduced from 28 to 19 or less, use of 50% cheaper base materials, giving overall reduction in PCB production costs of 25%; this in a European market of 3.2 bn ECU which is losing
competitiveness compared to the Pacific Rim.

Environmental Impact Reductions in waste water and solvent emissions by around 10 million l/year, use of formaldehyde plating baths eliminated, as would be use of acid and ammoniacal etchants (80 million l/year). Recycling of base materials (not presently possible) would save 25M ECU per year assuming 10% replacement of current technology.

The project will develop materials and automated processes for the production of two different types of additive circuitry to meet market needs:

i. Lower cost, lower resolution circuitry with 150 250 micron tracks and spaces by screen printing and UV curing of conductive and dielectric layers.

ii. High resolution circuitry with 25 100 micron tracks and spaces by using photoresist techniques.

A patent application covering aspects of this work has been filed by one of the partners; this application concerns a method of anchoring metallic particles to a substrate so that good bond strength between the conductive material and the basic substrate is obtained without sacrifice of conductivity (samples show resistance 1 x 10 5 ohm cm) and such that further treatment gives melting points in the region of 250 300 C thus enabling mass soldering of components without damage to the conductive tracks.

The technical work will be split into six workpackages which cover the development of materials and processes, performance and reliability testing and, finally, verification in demonstration end use
applications that meet identified market needs. A vertically integrated consortium has been formed to carry out the work, consisting of materials manufacturers, a process specialist, a PCB manufacturer, end users from different market sectors and an R. and D. performer. Each partner will contribute to exploitation of the project results in their own specialist field or market sector.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Coates Electrographics Ltd
Address
Norton Hill
BA3 4RT Bath
United Kingdom

Participants (4)

Alcatel Mobile Phones
France
Address
32,Avenue Kléber 32
92707 Colombes
Coates Screen Inks GmbH, Wiederhold Siebdruckfarben aus Nürnberg
Germany
Address
69,Am Stadtpark 69
90409 Nürnberg
Magneti Marelli SpA
Italy
Address
V. A. Borletti 61-63
20011 Corbetta
National University of Ireland, Cork
Ireland
Address
Prospect Row
30 Cork