Embedded Heterogeneous Hybrid PCB Structure
Original Publication Date: 2010-Sep-21
Included in the Prior Art Database: 2010-Sep-21
The idea is to embed one or more secondary printed circuit PCBs within a larger primary PCB, thus creating a hybrid PCB which allows for an optimum combination of what may otherwise be incompatible technologies (different layer counts, stackups, materials, line/space widths, copper thicknesses, etc.). The process is as follows: 1) The secondary PCB is fabricated independently of the larger primary PCB. The secondary PCB may be made with different materials, stackups, layer counts, etc, but should be similar in overall thickness to the primary PCB. 2) Before final lamination, a cavity or cutout is made in the larger PCB substrate. 3) The secondary PCB is fitted into the cutout, and the two are bonded together with prepreg and outer metal foil using heat and pressure in a lamination cycle. 4) After lamination, electrical connections to the embedded substrate may be made using microvias and/or standard vias connected with outer metal traces. Fine registration of the vias, microvias, or outer layer metal pattern may be locally registered to the embedded substrate if required using alignment fiducials.
Embedded Heterogenous Hybrid PCB Structure
By David Meyer
This document describes a method to embed heterogenous printed circuit board (PCB) structures to create a hybrid PCB with combined properties not otherwise possible with conventional PCB fabrication methods.
While normally a printed circuit board (PCB) is fabricated with a uniform physical structure (dielectric material, number of metal layers, etc.) throughout the entire board, sometimes various aspects of a PCB design may have physical requirements that are at odds with each other. For example, one section of the board design may have a need for very thick copper for heat sinking or current-carrying purposes, and another area may have a requirement for thinner copper due to the presence of fine lines and spaces. Another scenario may involve the need for one section of the PCB to be made with one type of dielectric material and another section to be made with a different type of dielectric material. Typically, a PCB would not be able to be made with the above mentioned requirements using conventional PCB fabrication methods. The same is true for different layer counts, via structures, etc. Another problematic situation may arise when a highly dense printed circuit board design needs to be tested and evaluated. Typically, the highly dense board design will be redesigned and integrated with a number of low-density test structures and/or connectors, which greatly increase the size and overall cost of the PCB (also known as a “mortable” board). A structure which allows for the high density product board to be physically embedded in and connected to the low density test board would improve product development efficiency and reduce overall costs.
The idea is to embed one or more secondary PCBs within a larger primary PCB, thus creating a hybrid PCB structure which allows for an optimum combination of materials and properties. Such benefits may include utilizing different dielectric materials in different areas of the PCB structure, limiting highly dense areas to small sections of the overall PCB (reducing overall cost), and allowing PCBs to be tested in their final desig...