Thin multi-chip flex module
View Patent ↗A multichip module comprises a multilayer substrate circuit having conductive patterns on its surface(s) to which microelectronic device(s) are attached. The conductive patterns include a series of electrical contacts adjacent to one edge of the substrate. The substrate is bonded to two rigid frames, one on each opposite surface. Each substrate has a series of castellations on one edge that are aligned and electrically connected to the respective contacts on the substrate, preferably by soldering. The castellations can serve as a self-aligning mechanism when the module is brought into contact with a low-profile pin array, and the module may be held in place on a motherboard by guide rails in a socket that engages the edges perpendicular to the castellated edge of the module. The module may further be provided with protective heat spreading covers.
1. A multichip module comprising:
a flexible multilayer dielectric substrate having a first surface and a second surface;
a conductive pattern on said first surface, said conductive pattern including a plurality of contacts adjacent to one edge of said substrate;
a conductive pattern on said second surface, said conductive pattern including a plurality of contacts adjacent to said one edge of said substrate;
a plurality of microelectronic devices attached to said substrate and operably coupled to said conductive patterns; and,
two substantially rigid frames extending around the periphery of said dielectric substrate, one on each of said first and second surfaces, said frames having a plurality of metallized castellations aligned with and electrically connected to respective contacts on said substrate.
2. The multichip module of claim 1 wherein said microelectronic devices are selected from the group consisting of: memory circuits, logic circuits, buffer devices, interface devices, optoelectronic devices, active and passive RF devices, and microprocessors.
3. The multichip module of claim 1 wherein said frames further comprise heat spreading covers.
4. The multichip module of claim 3 wherein said covers provide electrical shielding.
5. The multichip module of claim 1 wherein said frames are connected to one another along a selected fold axis so that by folding about said axis said rigid frames may be brought together to enclose said flexible multilayer dielectric substrate.
6. The multichip module of claim 1 wherein said metallized castellations are configured to engage respective pins in a mating socket.
7. The multichip module of claim 1 wherein the side edges of said frames are configured to engage guide rails in a socket and said socket is configured to hold said castellations in contact with corresponding pins on a motherboard.
8. A method for making a multichip module comprising the steps of:
forming a flexible dielectric substrate having a first surface and a second surface;
forming a conductive pattern on said first surface, said conductive pattern including a plurality of contacts adjacent to one edge of said substrate;
forming a conductive pattern on said second surface, said conductive pattern including a plurality of contacts adjacent to said one edge of said substrate;
attaching a plurality of microelectronic devices to said substrate and operably coupled to said conductive patterns; and,
attaching two substantially rigid frames extending around the periphery of said dielectric substrate, one on each of said first and second surfaces, said frames having a plurality of metallized castellations aligned with respective contacts on said substrate.
9. The method of claim 8 wherein said rigid frames are attached to said dielectric substrate by adhesive bonding.
10. The method of claim 8 wherein said substrate is extended beyond the castellated edge of said frames.
11. The method of claim 10 further comprising the step of:
passing the castellated edge of said frame through a solder bath to form a solder connection between each of said metallized castellations and its respective contact on said substrate.