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Browse Prior Art Database

Improved Processes and Materials for Filling Low Dielectric Power Cores

IP.com Disclosure Number: IPCOM000035738D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Ellis, TL: AUTHOR [+2]

Abstract

Disclosed is a process for filling the clearance holes and isolation slots in power cores made from thick copper and low dielectric constant insulating materials. The materials used to fill the holes drilled and/or milled in the power cores prevent voids from being formed in the multilayer printed circuit boards that could lead to short circuits between power layers.

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Improved Processes and Materials for Filling Low Dielectric Power Cores

Disclosed is a process for filling the clearance holes and isolation slots in power cores made from thick copper and low dielectric constant insulating materials. The materials used to fill the holes drilled and/or milled in the power cores prevent voids from being formed in the multilayer printed circuit boards that could lead to short circuits between power layers.

In a typical embodiment, the multilayer printed circuit structure is fabricated from power assemblies, using a series of processes as depicted in the figure:

(Image Omitted)

1. A raw power core is laminated from a thick copper sheet, a sheet of low dielectric constant insulating material, and a thin copper sheet.

2. The clearance holes are drilled in the raw core where plated through holes will be drilled in the multilayer printed circuit board. A fill mask is made by drilling clearance holes in a thin copper sheet in the same locations as the holes in the raw core. This step can be done at the same time as the preceding step. The first set of isolation slots are milled in the raw core and the fill mask. The isolation slots are needed to form an electrical isolation border around the active area of the power plane.

3. The power core, fill mask, and an appropriate number of sheets of filler material are laid up between two sheets of thin copper for lamination.

4. The clearance holes and isolation slots are filled with an insulating material by a lamination process. When placed under...