Contactless interconnection system

A contactless interconnecting system is provided between a computer chip package and a circuit board. The chip package has a substantially planar lower surface with a pattern of discrete terminal lands. The circuit board has a substantially planar upper surface spaced from and generally parallel to the lower surface of the chip package. A pattern of discrete circuit pads on the upper surface are aligned with the terminal lands. A plurality of discrete interposer members are disposed between the terminal lands and the circuit pads and are in a pattern corresponding to and aligned with the aligned patterns of the terminal lands and circuit pads. The interposer members are preferably of a material having a higher dielectric constant that of the material filling the gaps between interposer members.

FIELD OF THE INVENTION

This invention generally relates to the art of electrical connections and, particularly, to a contactless interconnecting system between a computer chip package and a circuit board.

BACKGROUND OF THE INVENTION

As semiconductor devices become more complex, the interconnections between the silicon wafer or die and appropriate circuit hardware continue to evolve and become more complex because of the difficulty of mechanical interconnections. This is due, in part, to the ever-increasing miniaturization and high density of electronic circuitry. Transmitted signals are becoming faster and faster (i.e., higher frequencies) and semiconductor packages are becoming thinner and thinner (i.e., closely compacted). In some anticipated applications, it may be practically impossible to use conventional interconnecting systems, i.e., typical metal contacts or terminals.

Typical mechanical interconnecting systems incorporate conventional terminal pins and sockets or other male and female configurations or interengaging spring connections. With such traditional metal-to-metal interconnections, it is essential to provide a wiping action between the terminals or contacts to remove contaminants or oxidants. Unfortunately, miniaturized semi-conductor interconnections are so small that such traditional mechanical interconnecting systems are not possible. Even traditional solder connections are difficult if at all possible because of the extremely complex hard tooling required for use with miniaturized or closely spaced components of a semi-conductor interconnecting system. In some applications, it may be necessary to rely on electrical or magnetic field coupling as a possible alternative, and the present invention is directed to satisfying this need and solving the problems enumerated above.

SUMMARY OF THE INVENTION

An object, therefore, of the invention is to provide a new and improved contactless interconnecting system, particularly such a system between a computer chip package and a circuit board.

In the exemplary embodiment of the invention, a computer chip package includes a substantially planar lower surface having a pattern of discrete terminal lands. A circuit board has a substantially planar upper surface spaced from and generally parallel to the lower surface of the chip package. The upper surface of the circuit board has a pattern of discrete circuit pads aligned with the terminal lands on the lower surface of the computer chip package. A plurality of discrete interposer members are provided between the terminal lands and the circuit pads. The interposer members are in a pattern corresponding to and aligned with the aligned pattern of terminal lands and circuit pads. The interposer members are of a material having a relatively high dielectric constant.

As disclosed herein, the terminal lands are on a lower surface of a wall of the computer chip package. The terminal lands are connected by vias through the wall to leads from a silicon wafer of the package.

In one embodiment of the invention, the interposer members are adhered either to the terminal lands or to the circuit pads. In another embodiment of the invention, the interposer members are supported by a planar carrier disposed between the lower surface of the chip package and the upper surface of the circuit board. The planar carrier may be fabricated of dielectric elastomeric material, and the interposer members may be overmolded in the planar carrier member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in greater detail, FIG. 1 shows a first embodiment of a contactless interconnecting system, generally designated 10 , between a computer chip package, generally designated 12 , and a circuit board 14 or other substrate, such as a printed circuit board. FIG. 2 shows a second embodiment of a contactless interconnecting system, generally designated 10 A, also between chip package 12 and circuit board 14 .

Computer chip package 12 in both embodiments 10 and 10 A includes a silicon wafer 16 mounted on an upper surface 18 of a wall 20 of a housing 22 within which the silicon wafer is disposed. A pattern of discrete terminal lands 24 are deposited on upper surface 18 of wall 20 and are connected by leads 26 to silicon wafer 16 . Terminal lands 24 are connected through wall 18 by respective vias 28 to a matching pattern of discrete terminal lands 30 on a substantially planar lower surface 32 of wall 18 of the chip package.

Circuit board 14 of either interconnecting system 10 or 10 A has a substantially planar upper surface 34 spaced from and generally parallel to lower surface 32 of chip package 12 . A pattern of discrete circuit pads 36 are disposed on upper surface 34 and are aligned with terminal lands 30 on lower surface 32 of the chip package. The circuit pads 28 are electrically connected to respective circuitry on the circuit board 14 .

The invention contemplates that a plurality of discrete interposer members 38 be disposed between terminal lands 30 and circuit pads 36 . Interposer members 38 are spaced from each other, as at gaps 40 , and are in a pattern corresponding to and aligned with the aligned patterns of terminal lands 30 and circuit pads 36 . The interposer members are preferably fabricated of a material having a high dielectric constant relative to the dielectric constant of the material in the gaps 40 to prevent coupling between catercornered terminal lands 30 and circuit pads 36 . In an embodiment, the dielectric constant of the interposer members 38 is at least an order of magnitude greater than that of the material in the gaps 40 . In another embodiment, the dielectric constant of the interposer members 38 is at least 200. However, as signal frequencies increase the magnitude of the dielectric constant required of the interposer members may decrease.

Interposer members 38 in the embodiment of FIG. 1 are supported by a generally planar carrier member 42 disposed in a parallel arrangement between lower surface 32 of the chip package and upper surface 34 of the circuit board. The planar carrier member may be fabricated of a dielectric elastomeric material, such as plastic or rubber. The interposer members may be overmolded in the planar carrier member. As previously mentioned, the dielectric constant of the interposer members 38 should be an order of magnitude greater than that of the carrier member 42 to prohibit catercornered coupling.

FIG. 2 shows a second or alternative embodiment of the contactless interconnecting system 10 A wherein planar carrier member 42 of the first embodiment ( FIG. 1 ) has been eliminated. In this second embodiment of FIG. 2 , interposer members 38 are adhered to either or both of terminal lands 30 and circuit pads 36 . For example, interposer members may be deposited onto either terminal lands 30 or circuit pads 36 by a suitable printing method. However, gaps 40 again are provided between the interposer members. Once again, the dielectric constant of the interposer members 38 should be an order of magnitude greater than any material (e.g., air) filling the gaps 40 to prevent catercornered coupling.

In both embodiments of the interconnecting systems 10 and 10 A shown in FIGS. 1 and 2 , respectively, interposer members 38 , 38 are discrete members and are separated, as at gaps 40 , 40 and described above. Preferably, the interposer members are of sizes substantially the same as the sizes of aligned terminal lands 30 and circuit pads 36 . Electrical signals are capacitively transferred from terminal lands 30 through the interposer members 38 , 38 to the circuit pads 36 . Gaps 40 , 40 between the interposer members with a lower dielectric constant than that of the interposer members provide a dielectric break between catercornered terminal lands 30 and circuit pads 36 . Since electrical signals prefer to be coupled through high dielectric constant materials, the signals will tend to not cross the gaps 40 , 40 between the interposer members of relatively higher dielectric constant materials. Therefore, the discrete or separated interposer members considerably reduce cross-coupling or cross-talk between catercornered sets of terminal lands 30 and circuit pads 36 .

It should be understood that the use of such terms as upper , lower , top , bottom , vertical and the like herein and in the claims hereof is not in any way intended to be limiting. Such terms simply provide a clear and concise description and understanding of the invention as viewed in the drawings. Obviously, interconnecting systems 10 and 10 A are omni-directional in use or application.