Circuit substrate and method for fabricating the same
AssigneeFujitsu Limited
InventorsOsamu Taniguchi, Yasuo Yamagishi, Koji Omote
Life of this patent
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Abstract
A circuit substrate comprises a glass substrate 16, through-holes 18 formed through the glass substrate 16 and via electrodes 20 buried in the through-holes 18. An opening width of the through-holes 18 is minimum inside the glass substrate and is increased toward both surfaces of the glass substrate 16. Accordingly, the detachment of the via electrodes 20 can be prevented without increasing the surface roughness of the inside walls of the through holes, and stresses generated in the core substrate can be mitigated.
Claims10
A method for fabricating a circuit substrate comprising the steps of forming a through-hole in a core substrate and burying a via electrode in the through-hole,
- in the step of forming the through-hole, the through-hole being defined by an inside wall of the through-hole and being formed so that the inside wall of the through-hole has a plane substantially parallel to the surface of the core substrate at least a part of the inside wall of the through-hole, and that an opening width of the inside wall of the through-hole is minimum inside the core substrate and increased toward both surfaces of the core substrate so that a perpendicular sectional form of the inside wall of the through-hole is made of straight lines all over the other part except for said part of the inside wall.
Dependencies are inferred from the claim text.