US 10,172,244 B1
Construction of printed circuit board having a buried via
Matteo Cocchini, Long Island City, NY (US); and Kyle I. Giesen, Beacon, NY (US)
Assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION, Armonk, NY (US)
Filed by INTERNATIONAL BUSINESS MACHINES CORPORATION, Armonk, NY (US)
Filed on May 9, 2018, as Appl. No. 15/975,726.
Int. Cl. H05K 3/42 (2006.01); H05K 1/11 (2006.01); H05K 3/46 (2006.01); H05K 3/06 (2006.01)
CPC H05K 3/421 (2013.01) [H05K 1/115 (2013.01); H05K 3/06 (2013.01); H05K 3/429 (2013.01); H05K 3/4614 (2013.01); H05K 2201/09536 (2013.01); H05K 2201/09572 (2013.01); H05K 2203/107 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method of constructing a printed circuit board having a buried via comprising: constructing a plurality of multilayer cores wherein each multilayer core comprises a sheet of cured dielectric material having a layer of metal on each side of the sheet of cured dielectric material; patterning each layer of metal in the plurality of multilayer cores to form wiring traces in each layer of metal; forming a plurality of sheets of uncured dielectric material; embedding a solder element in at least one sheet of the uncured dielectric material; alternately stacking the plurality of multilayer cores with the plurality of sheets of uncured dielectric material between each multilayer core, the at least one sheet of the uncured dielectric material having the embedded solder element positioned so as to be aligned with wiring traces in adjacent layers of metal in adjacent multilayer cores; heating the solder element so as to cause the solder element to melt and create electrical continuity between the wiring traces; and hot pressing the stack of multilayer cores and sheets of uncured dielectric material to cause curing of the sheets of uncured dielectric material, wherein after hot pressing, locally heating the solder element to cause the solder element to melt.