MECOS: Melamine composite for shielding

• Unité de recherche: PCRD EU
• Numéro de projet: 97.0508
• Titre du projet anglais: MECOS: Melamine composite for shielding

Mots-clé (Anglais)

Composite; thermoset; melamine-formaldehyde; eletromagnetic shielding; dimensional stability

Autre Numéro de projet (Anglais)

EU project number: BRPR-CT98-0726

Programme de recherche (Anglais)

EU-programme: 4. Frame Research Programme - 2.1 Industrial and materials technologies

Description succincte (Anglais)

See abstract

Autres indications (Anglais)

Full name of research-institution/enterprise:
EPF Lausanne
Département des Matériaux
Laboratoire de Technologie des Composites et Polymères

Partenaires et organisations internationales (Anglais)

Perstorp, DSM Research, Nokia, Télécommunications,
Chalmers University of technology

Résumé des résultats (Abstract) (Anglais)

There is an increasing need to properly shield electronic circuitry from electromagnetic interference (EMI). It has been the intention within this project to develop a new cost-effective EMI-shielding material technology to replace metals for racks and enclosures of electronic circuits and components, using long fibre-reinforced melamine-formaldehyde (MF) composites processed by compression moulding. Such a technology should provide good shielding and mechanical performance at a reduced total cost, while allowing greater design freedom. However, the quality of the moulded parts is highly dependant on the material chosen and on the internal stresses caused by the dedicated EMI shielding phase during processing.

Two new material systems have been developed during the project; a laminated copper foil/MF technology and an SMC-type carbon fibre chopped strand moulding compound. The former gives excellent shielding performance in parts involving limited flow during moulding, whereas the latter has improved flow characteristics. Both show encouraging cost performance in relation to existing shielding technologies.

The primary role of the LTC-EPFL within this consortium has been to evaluate process-induced internal stresses in the moulded parts and to predict the post-moulding dimensional stability resulting from these stresses.

For the evolution of internal stresses in polymeric materials, both a stress generating and a stress relaxing mechanism must be considered. Both of these mechanisms are governed by the viscoelastic properties of the material. A numerical tool for predicting internal and residual stresses in polymeric materials which accounts for anisotropy, viscoelasticity and heterogeneity ('ANVIS'), previously developed at LTC-EPFL, has been modified with
- a three-dimensional formulation for the calculation of complex geometries with out-of-plane features, as in the mouldings produced during the project
- a module adapted to the solidification behaviour of thermoset-matrix composites, accounting for the cure kinetics and viscoelastic properties.
LTC-EPFL has participated in the study of the quality of parts moulded from the new materials developed within the project. This has involved the investigation of process-induced internal stresses and their effect on the dimensional stability of the parts after moulding, as well as how to resolve these problems by using predictive tools and engineering guidelines for material and process selection during the design of parts. The work has implicated collaboration with all of the project partners.

In addition the life cycle of the material, in particular its recyclability, has been investigated.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0508