A substrate having multiple metal layers is disclosed. The substrate includes a plurality of metal layers disposed in different levels. The plurality of metal layers includes a lower metal layer, a middle metal layer situated overlying the lower layer, and an upper metal layer situated overlying the middle metal layer. A solder mask covers the upper metal layer. A reference plane is arranged in the lower metal layer. A trio of signal traces is arranged in the middle metal layer. The trio of signal traces comprises at least a pair of differential signal traces. A plurality of reference nets is arranged in the middle metal layer.