BGA substrate via structure
AssigneeTexas Instruments Incorporated
InventorsJohnny Cheng, Joyce Hsu
Life of this patent
Estimating the term…
Abstract
Typically, primary electrical connection between a semiconductor chip and an external solder ball contact on a Ball Grid or Chip Scale Package is by way of a via extending through a dielectric substrate. The aspect ratio between via diameter and depth is critical for reliable and high yield solder bail attachment during printed circuit board assembly. Excellent ball adherence and reliability of BGA solder ball contacts is achieved through controlling the aspect ratio of the substrate vias by partially plating a solid solderable conductor core in each via. An improved via structure is disclosed wherein the depth of the via is reduced without the negative effects of alternate methods, such as thinner substrates, or wider vias.
Claims16
A ball grid array substrate for semiconductor devices which comprises:
- a) a dielectric substrate having a first and second major surface with one or more apertures through said substrate,
- b) metallization patterned on the first surface of said substrate contacting each of said vias, and including one or more bonding pads for providing interconnection to said semiconductor device,
- c) a core of solderable metal within each of said apertures intimately connected to said patterned metallization, and extending through a minimum of one-third the substrate thickness, and
- d) a solder ball extending into said via from the second surface, making intimate contact with said solderable metal.
A via structure for attachment of a solder ball including;
- a dielectric base having one or more apertures,
- a solid core of solderable metal extending from one surface to a minimum of one third the thickness of said base, and
- a height to width aspect ratio of 0.3 to 1.0 or less.
Dependencies are inferred from the claim text.