Fabrication of Bumped Connectors

To reduce the cost of flip chip interconnection, an organic process was developed at Epoxy Technology Inc. [81]. The polymer flip chip technology (PFc ) a polymer dielectric paste and an electrically conductive adhesive. 

After the polyimide layer is cured, the conductive polymer paste is printed to the substrate in order to fill the holes over the metal pads and then cured (Fig. 32(b)). Using the same stencil and conducting paste, the polymer bumps are then screen printed on top of the conductive polymer pads and cured (Fig. 32(c)). Current printing techniques allow production of 50-100 p,m diameter bumps, 30-50 p.m high, with a centre-to-centre pitch of 125-150 p,m, and flat, conic, or hemispherical shapes. Once the bumps are cured and the dice sawed, 

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