Abstract: A die-mounting substrate and method incorporating dummy traces for improving mounting film planarity makes the use of film attach possible with a simplified manufacturing process and in applications where film-attach was not previously practical. The die-mounting substrate includes dummy traces that are generated along with signal traces extending into the die mounting area of the substrate. The dummy traces are designed according to the same design rules as the signal traces and are disposed in otherwise empty regions between signal traces and vias within the die mounting area. The result is die mounting area without regions empty of signal traces that previously either lack conductor or are filled completely with conductor, either of which will result in surface variation that compromises the film bond.

Abstract: The invention discloses a method of making solder ball mounting pads on a substrate that have better ball shear performance, ball thermal cycle reliability, ball attach yield, and ball positional tolerances, than the solder ball mounting pads of the prior art. The method includes providing a sheet of material having a layer of metal thereon, and patterning the layer to define a solder ball mounting pad therein. The pad includes a central pad having at least two spokes radiating outward from it. An insulative mask is formed over the metal layer, and an opening is formed in the mask such that the central pad and an inner portion of each of the spokes is exposed therethrough, and an outer portion of each of the spokes is covered by the mask. In one embodiment, the central pad, spokes, and opening in the mask are shaped and arranged with respect to each other such that the pad and exposed portion of the spokes form a radially symmetrical pattern within the opening.