Micro-Spring Chip Attachment Using Solder-Based Interconnect Structures

摘要

Standard solder-based interconnect structures are utilized as mechanical fasteners to attach an IC die in a “flip-chip” orientation to a support structure (e.g., a package base substrate or printed circuit board). Electrical connections between the support structure and the IC die are achieved by curved micro-springs that are disposed in peripheral regions of the IC die and extend through a gap region separating the upper structure surface and the processed surface of the IC die. The micro-springs are fixedly attached to one of the support structure and the IC die, and have a free (tip) end that contacts an associated contact pad disposed on the other structure/IC die. Conventional solder-based connection structures (e.g., solder-bumps/balls) are disposed on “dummy” (non-functional) pads disposed in a central region of the IC die. After placing the IC die on the support structure, a standard solder reflow process is performed to complete the mechanical connection.

主权项

1. A circuit assembly comprising:
a support structure including a first support contact pad and a second support contact pad disposed on an upper surface thereof, said first support contact pad being electrically connected to at least one conductor disposed on said support structure; a device mounted on the support structure such that a lower surface of the device faces the upper surface of the support structure, the device including first and second device contact pads that are disposed on the lower surface, said first device contact pads being electrically connected to at least one conductive structure disposed on said device; a curved micro-spring disposed in a gap region defined between the upper surface of the support structure and the lower surface of the device, the micro-spring including a first end that is electrically connected to the first device contact pad, a second end that is electrically connected to the first support contact pad, and a curved body portion extending between the first and second ends; and a solder-based interconnect structure having a first end portion connected to the second support contact pad, a second end portion connected to the second device contact pad, and a body portion extending between the first and second end portions such that the device is rigidly mechanically secured to the support structure by said solder-based interconnect structure.