Apparatus and method for mounting BGA devices
AssigneeAltera Corporation
InventorMohammad Eslamy
Life of this patent
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Abstract
A surface-mount device attach method for attaching solder ball-grid array or solder column-grid array surface-mount devices to a printed circuit board where the conventional solder mask structure is replaced with a layer of plated nickel to prevent printed circuit board warping caused by the mismatch in the coefficients of thermal expansion between the conventional solder mask and the printed circuit board. A native nickel-oxide layer that forms on the surface of the exposed portions of the plated nickel layer functions as a solder dam.
Claims25
A printed circuit board having at least one surface-mount-device bonding site comprising:
- at least one surface having said at least one surface-mount device bonding site;
- at least one base conductor layer plated on a portion of said surface;
- at least one plated nickel outer layer on said base conductor layer;
- and
- an array of bonding pads formed by at least one selectively plated gold layer on a portion of said plated nickel outer layer and leaving a remainder of said plated nickel outer layer exposed to form a layer of native nickel-oxide, wherein said selectively plated gold layer on each of said bonding pads is substantially surrounded by said layer of native nickel-oxide and said array of bonding pads form said at least one surface-mount device bonding site.
A method of forming a printed circuit board for mounting surface-mount devices comprising:
- providing a printed circuit board having at least one surface having at least one surface-mount device bonding site;
- plating at least one base conductor layer on a portion of said surface;
- plating at least one plated nickel outer layer on said base conductor layer;
- and
- selectively plating at least one layer of gold on a portion of said plated nickel outer layer to form an array of gold bonding pads at said surface-mount device bonding site and leaving a remainder of said plated nickel outer layer exposed to form a layer of native nickel-oxide.
A printed circuit board having at least one surface-mount device bonding site comprising:
- at least one surface having said at least one surface-mount device bonding site;
- at least one base conductor layer plated on a portion of said surface;
- at least one adhesion promoting layer plated on said base conductor layer wherein said adhesion promoting layer has a coefficient of thermal expansion that is substantially similar to that of said printed circuit board;
- and
- an array of bonding pads formed by at least one selectively plated gold layer on a portion of said adhesion promoting layer, wherein said adhesion promoting layer is a plated nickel outer layer and a portion of said plated nickel outer layer not covered by said selectively plated gold layer is exposed to form a layer of native nickel-oxide, wherein said selectively plated gold layer on each of said bonding pads is substantially surrounded by said layer of native nickel-oxide and said array of bonding pads form said at least one surface-mount device bonding site.
A method of forming a printed circuit board for mounting surface-mount devices comprising:
- providing a printed circuit board having at least one surface having at least one surface-mount device bonding site;
- plating at least one base conductor layer on a portion of said surface;
- plating at least one adhesion promoting layer on said base conductor layer wherein said adhesion promoting layer has a coefficient of thermal expansion that is substantially similar to that of said printed circuit board;
- and
- selectively plating at least one layer of gold on a portion of said adhesion promoting layer to form an array of gold bonding pads at said surface-mount device bonding site, wherein said adhesion promoting layer is a plated nickel outer layer and a portion of said plated nickel outer layer not covered by said selectively plated gold layer is exposed to form a layer of native nickel-oxide, Wherein said selectively plated gold layer on each of said bonding pads is substantially surrounded by said layer of native nickel-oxide and said array of bonding pads form said at least one surface-mount device bonding site.
Dependencies are inferred from the claim text.