The effect of sputtered interface metallic layers on reinforced core laminate making build-up structures

In conventional printed circuit board manufacturing, pressure and heat are used to attach the copper layer to the laminate. To achieve narrow lines the additive method is used instead. To produce the seed metal, a palladium bath is quite often used. This method is used in conventional PCB production. In our paper we suggest a new method of arriving at a very thin and even surface by sputtering. The sputtering process is done in a simple chamber with an argon atmosphere. The process is rapid (only few tens of seconds) and inexpensive, since the produced layer is very thin. This sputtered metal acts as an adhesion layer, and copper can be grown on this layer either through electrolysis or by electroless means. In the adhesion test, the sputtered and copper-coated specimens were subjected to a peel strength test. It has been noted that the adhesion of sputtered metal to the epoxies differs greatly depending on the metal used. The effects of heating after sputtering have also been identified. It has also been noted that the treatment of the surface has a significant effect on adhesion. In this paper we describe the sputtering method, the results of the peel strength tests and the treatments, which act on the adhesion of the metal to the base laminates.