Patent attributes
A ceramic substrate has, on its surface, a multilayer wiring division, on which micro cantilever type probes are fixed. The multilayer wiring division has the first conductor layer, which includes through-hole junction pads, flatness improvement rings surrounding the through-hole junction pads and a grounding region further surrounding the flatness improvement rings. Since the flatness improvement rings are located around the through-hole junction pads, the surface of the first insulating layer, which is located above the first conductor layer, is free from severe undulation even near the through-hole junction pads. Accordingly, the multilayer wiring division has less irregularity in shape as a whole, and thus the probe mounting pads on the surface of the second insulating layer do not slope but keep almost horizontal. The probe unit substrate according to the invention has an advantage of less surface undulation and having non-sloping probe mounting pads without using a complicated manufacturing process.
