Protective Shield Solder Dam for Substrates
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
A pre-punched plastic film 1 is heat and/or pressure bonded to the substrate 2 to act as a protective shield over the conductors 3 and any thick film resistors (not shown). Film also doubles as a solder dam around surface soldered components 4. Windows 5 are pre-punched on the film. By suitable selection of the material for the plastic film, it is possible to use high melting temperature solders, such as 95% lead/5% tin. It is also possible to operate such a substrate, populated with heat dissipating electronic components 4 at high temperatures (150 degrees C and above). Use of pre-punched film will increase production throughput over the slow heat cured, screen-printed thermoset materials. Polyether sulfone and thermoplastic polyimide are examples of materials for the plastic film 1.