The Jastac process
The Jastac process enables metal components to be punched through metal or laminate sheets without the necessity for pre-drilling or pre-punching of holes, and is widely used for assembling tags onto printed circuit boards and other electronic assemblies with remarkable savings in cost.
Tags for printed circuit boards are of square or rectangular section and are available clean or plated. These tags take many forms, e.g. stand-off, feed-through, take-off etc., and the connection may be made by wrapping, soldering or welding. The tags are inserted by press-operated single or multi-insertion tools, the latter being tailor-made to suit a particular board layout.
The operation of a single insertion tool is described as follows: The punch section is clamped in the ram of the press, the die is clamped to the base of the press and aligned with the punch. The tag is loaded into the punch with the insertion leg pointing towards the die. The printed circuit board is placed squarely on the die and the pressure is applied. The tag punches its way through the pcb, rolling copper down as it passes through. When the tag has penetrated the board, it comes into contact with the die. The die has a round hole of smaller diameter than the diagonal of the tag, so that the action of the tag entering the die is to peen back the four corners. The insertion leg has a slight taper into which the board material flows, and at the end of the taper, at the shoulder, there is a small radius which rolls the copper down onto the board. The shoulder of the tag presses on top of the copper, and the result is a good electrical connection and a gas-tight joint.
For most combinations of tag and board material, no pre-drilling is required, but some very hard grades of fibre-glass boards have to be pre-dilled to accept very slender tags. Feed-through tags require a small hole drilled through to miss the wire-wrapping section, the wider portion at the end of the wire-wrapping section punching into the board and becoming secured by the taper and the peening action of the die.