Abstract: A description is given of a method of providing a synthetic resin capping layer on a printed circuit, said capping layer exhibiting a variation of the mechanical properties in a direction at right angles to the capping layer. Said capping layer is manufactured by injecting moulding of a foam-forming injection-moulding material. This economically attractive method provides circuits which are excellently protected against mechanical and thermal stresses which may arise during operation. In addition, circuits having a synthetic resin capping layer can be used to reduce the thickness and the weight of portable devices, such as a mobile telephone.