Electronic thin film circuit unit and method of making the same

Claim 1

In a thin film electronic circuit unit comprising a substrate plate of insulating material, a patterned layer of a valve metal partly covering the substrate plate in accordance with a first and a second pattern, said first and second patterns being contiguous to each other in at least one location and respectively defining a first and a second portion of said valve metal layer, said first portion providing circuit elements and said second portion providing connecting conductors and areas for external contact and being provided with metallization, said metallization of said second valve metal layer portion including a first copper layer (4) on top of said valve metal layer, an intermediate layer (5) of a diffusion barrier metal on top of said first copper layer and a second copper layer (6) on top of said diffusion barrier metal layer, and a soft solder layer (7) provided on top of said metallization, the improvement wherein: said metallization further comprises five layers (4, 5, 6, 10, 11) of which one is a nickel layer (10) located on top of said second copper layer (6) and another is a gold layer (11) superimposed on said nickel layer (10).