Laser Manufacturing of Mechanical Structures in Flexible Substrates

In microelectronics industry the main driving forces are to improve performance and to lower cost. From the performance point of view the small distances between chips together with the short interconnection routes have of great importance in order to achieve faster operation. The application of polymeric materials for the insulating and protective layers of interconnect substrates is beneficial to the performance and to the cost of a circuit module as well [1-2]. An advanced technology for the fabrication of very high density interconnects applies multi-folded 3D (three-dimensional) microvia flexible substrates, where laser via and bending window generation technology has particular significance [3]. Bending window generation is a unique application of laser material processing. A bending window can be used in a flexible circuit to define the exact position of the bending edge as well as the radius and the angle of the deformation. It is produced by reducing the thickness of the flexible substrate in a well-defined, narrow window. The paper gives an overview on laser processing of flexible polymer materials to produce bending windows for multi-folded 3D substrates.