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AssigneeInternational Business Machines Corporation
InventorsPeter J. Brofman, Shaji Farooq, John U. Knickerbocker, Scott I. Langenthal, Sudipta K. Ray, Kathleen A. Stalter
Estimating the term…
A method of and device for preventing short circuits between solder joints in flip chip packaging. The dielectric interposer of the present invention has a plurality of apertures or vias which correspond to the I/O pads on a chip and substrate. Preferably, the interposer comprises a polyester film, glass, alumina, polyimide, a heat curable polymer or an inorganic powder filler in an organic material. More preferably, the interposer contains an adhesive or has adhesive layers disposed on the linear surfaces of the interposer. Cone shaped solder elements are formed within the apertures of the interposer. The dielectric interposer is positioned between a chip and substrate in an electronic module and thermally reflowed to create an electrical and mechanical interconnection. The interposer prohibits contact between the solder joints by isolating each of the joints and corresponding bonding pads. The interposer also prevents over compression of the solder joints by acting as a stand off.
A method of fabricating an interposer for electronic packaging comprising the steps of
An interposer for chip to substrate joining comprising
A method of assembling electronic modules comprising the steps of:
A flip chip electronic module comprising
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Backward citations are indexed for grants only.
Leadless components: having an array of bottom contacts, e.g. pad grid array or ball grid array components
Vias, e.g. via plugs: through-vias
Other objects, e.g. metallic pieces: interposers
Other objects, e.g. metallic pieces: frame holders
Term end not estimated
1. Field of the Invention
This invention relates to the manufacture of semiconductor devices, and in particular, to a method of and device for preventing short circuits between solder joints in flip chip packaging.
2. Description of Related Art
The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:
FIG. 1 is a top plan view of a substrate of the prior art.
FIG. 2 is an elevational cross-sectional view of an electronic module of the prior art.
In describing the preferred embodiment of the present invention, reference will be made herein to FIGS. 1-6 of the drawings in which like numerals refer to like features of the invention. Features of the invention are not necessarily shown to scale in the drawings.
In FIG. 1 there is shown a top plan view of a substrate 10 of the prior art used in flip chip packaging. On the surface of the substrate 10 are bonding pads 14 which correspond to the I/O pads on the substrate to be electrically and mechanically connected to corresponding I/O pads on a chip. Solder balls 17 are formed on substrate 10 as the interconnections. Normally, the solder balls 17 flow within the boundaries specified by the bonding pads 14, however, solder balls and bonding pads are often aligned such that shorts 19 occur as shown in FIGS. 1 and 2. FIG. 2 is a partial cross-sectional view of an electronic module having substrate 10 with bonding pads 14a, connected to chip 12 having corresponding bonding pads 14b by solder bumps 17. If chip 12 is placed on substrate 10 during formation of the flip chip package with excessive force, there can be an over compression of the solder bumps 17. This over compression can lead to shorts in area 19 wherein the solder bumps 17 are misshapen to such a degree that two solder bumps can come in contact with each other.
FIG. 3 shows a free-standing polymer interposer 30 of the present invention. Preferably, the interposer 30 is made from a dielectric material 33. Examples include polyester films such as Kapton™ or Mylar™, organic polymers such as polyimide, an inorganic powder filler in an organic polymer, ceramic, inorganic materials such as glass (SiO2) or alumina (Al2O3), or any other appropriate material which is non-conductive and which may or may not be heat curable. The interposer 30 has a plurality of apertures or vias 35 which correspond to the I/O pads on a chip 42 and substrate 40 in the resultant electronic package shown in FIGS. 4 and 5. For the ease of differentiation in the drawings, the apertures 35 are shown as circles and bonding pads 44 are shown as squares although any shape may be utilized on practicing the invention.