International Business Machines Corporation

Richard C Senger

Voya Rista Markovich

John M Lauffer

Kishor V Desai

Donald P Seraphim

Harold Kohn

Eric P Dibble

Richard Stuart Zarr

Gary Paul Vlasak

Steven L Hanakovic

Daniel S Niedrich

A printed circuit board has a plurality of layers. A first surface land is formed on an inner layer. A dielectric material is laminated on the inner layer. A second surface land is formed on the dielectric material overlapping the inner surface land or positioned along the border of the inner surface land. A hole is etched in the dielectric material exposing the first surface land to the second surface land. The second surface land does not completely surround the hole. A component lead is positioned over the second surface land. Solder is reflowed into the hole to interconnect the surface lands to each other and to the component lead. Because the second surface land does not completely surround the hole, the solder does not bridge across the hole and thereby forms a solid connection between the first and second surface lands.

Electronic circuit cards with solder-filled blind vias

A multi-layer printed circuit board or card including a plurality of circuitized power cores, the circuitized power cores include a layer of an electrically conductive material having a layer of electrically insulating material attached on both sides thereof. The circuitized power cores also include a plurality of plated through holes formed therethrough in substantially the same pattern on each circuitized power core. The circuitized power cores are parallel to each other such that corresponding plated through holes in the two circuitized power cores are co-linear. A plurality of substantially spherical balls are located between the circuitized power cores and are in contact with the corresponding plated through holes on facing cards. The balls have a diameter slightly larger than the opening of the plated through holes and are made of an electrically conductive material.

Method of making a printed circuit board or card

Process is described for applying large quantities of solder to small areas, such as the lands in a high density card, to which it is intended to surface mount electronic devices or directly attach circuitized chips. The land area is temporarily extended by depositing a relatively thin layer of metal beyond the perimeter of the land, wave soldering to deposit excess solder on the extended land region, and reflow, whereby the thin layer of metal dissolves into the solder, causing the solder to retract to the dimensions of the original land. Because the volume of solder is increased, the strength and reliability of the solder joint is greatly improved.

Applying solder to high density substrates

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Vestal, NY, United States of America

Richard C Senger