Full additive process with filled plated through holes
AssigneeInternational Business Machines Corporation
InventorsAnilkumar C. Bhatt, Voya R. Markovich, Irving Memis, William E. Wilson
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Abstract
The present invention provides a printed circuit board and a method for the production of a printed circuit board having fine-line circuitry and greater aspect ratio on a subcomposite with plated through holes. A method provides for additive plating on a subcomposite having filled plated through holes. Fine-line circuitry is achieved via electroless deposition onto a dielectric substrate after the through hole is plated and filled. Fine-line circuitry may be routed over landless, plated through holes thereby increasing the aspect ratio and the available surface area for additional components and wiring.
Claims19
A printed wiring board comprising:
- (a) a dielectric substrate having upper and lower surfaces;
- (b) at least one landless filled plated through hole disposed through the substrate from the upper to the lower surface, the through hole having a first diameter;
- (c) the through hole further comprising an inner surface extending from the upper to the lower surface, the inner surface plated with a conductive metal plating, the inner surface plating having an upper end aligned with the substrate upper surface and a lower end aligned with the substrate lower surface;
- (d) the through hole filled with a filler composition having upper and surfaces, wherein the filler composition upper surface is aligned with the dielectric substrate upper surface and the through hole inner surface plating upper end, the filler composition upper surface, substrate upper surface and inner surface plating upper end thereby defining a smooth upper subcomposite surface;
- and
- (e) an additively plated unetched first circuitry line having a bottom surface plated directly onto the at least one plated through hole inner surface plating upper end and said upper subcomposite surface and thereby electrically connected to said plated through hole, the first circuitry line further comprising a top surface, the first circuitry line bottom surface and first circuitry line top surface having a common line width approximately equal to or less than the first diameter.
A printed wiring board comprising:
- (a) a dielectric substrate having upper and lower surfaces;
- (b) at least one landless filled plated through hole disposed through the substrate from the upper to the lower surface, the through hole having a first diameter:
- (c) the through hole further comprising an inner surface extending from the upper to the lower surface, the inner surface plated with a conductive metal plating, the inner surface plating having an upper end aligned with the substrate upper surface and a lower end aligned with the substrate lower surface;
- (d) the through hole filled with a filler composition having upper and surfaces, wherein the filler composition upper surface is aligned with the dielectric substrate upuer surface and the through hole inner surface plating upper end, the filler composition upper surface, substrate upper surface and inner surface plating upper end thereby defining a smooth upper subcomposite surface;
- and
- (e) an additively plated unetched metal pad having a bottom surface plated directly onto the at least one plated through hole inner surface plating upper end and said upper subcomposite surface and thereby electrically connected to said plated through hole, the unetched metal pad further comprising a top surface, the unetched metal pad bottom surface and unetched metal pad top surface having a common pad width approximately equal to the first diameter;
- and
- (f) a first circuitry plated onto the upper subcomposite surface and electrically connected to the unetched metal pad.
Dependencies are inferred from the claim text.