Semiconductor core layer including glass sheet having edge sealant structure and method of making same

A microelectronic assembly including:

• a package substrate including:
• a sheet including glass;
• build-up layers respectively on a top surface and on a bottom surface of the sheet;
• structures defining electrically conductive pathways within the sheet and within the build-up layers;
• and
• a ribbon-shaped edge structure in recesses defined at lateral edges of the sheet and defined with respect to lateral edges of the build-up layers, the ribbon-shaped edge structure extending in a direction along a thickness of the sheet, having a lateral edge surface facing away from the sheet, and comprising an edge structure material not including glass and not including metal;
• and
• one or more dies attached to the package substrate and coupled to the structures defining electrically conductive pathways.

A method of fabricating core layers of microelectronic package substrates, the method including:

• providing panel structure including:
• a plurality of sheets including glass and defining saw streets therebetween;
• and
• build-up layers respectively on a top surface and on a bottom surface of individual ones of the plurality of sheets;
• and
• structures defining electrically conductive pathways within the plurality of sheets and within the build-up layers;
• singulating the panel structure along the saw streets to yield a plurality of units, individual ones of the units including a corresponding one of the plurality of sheets and corresponding ones of the build-up layers;
• providing recesses at lateral edges of said corresponding one of the plurality of sheets;
• providing an edge structure material within the recesses to form respective ribbon-shaped edge structures therefrom, individual ones of the ribbon-shaped edge structures defined with respect to lateral edges of corresponding ones of the build-up layers, extending in a direction along a thickness of said corresponding one of the plurality of sheets, and having respective lateral edge surfaces facing away from said corresponding one of the plurality of sheets.