Abstract: A relatively brittle sheet material, for example, a printed circuit board substrate, is subdivided into sections the boundaries of which are defined by apertures which permit the substrate to be fractured at the boundaries. Each aperture has side walls which intersect at points aligned along a separation line. Bending stresses are concentrated at the intersecting side walls to provide a clean straight fracture along the boundary.

Abstract: A heat sink for a transistor is provided which comprises a long and a short vertical portion joining a sloped upper surface. The transistor is bolted to the sloped surface with its leads extending below the bottom of the vertical portions. The transistor leads are inserted into a large slot in a printed circuit board, and the assembly is rotated to engage tabs on the short vertical portion and then the long vertical portion in mating holes in the printed circuit board. The assembly will then snap into place, with the transistor oriented at an oblique angle with respect to the plane of the board. There is no need to bend or preform the leads, and the oblique orientation of the transistor reduces the horizontal and vertical forces of vibration and thermal expansion and contraction by a factor of two.