Abstract: The specification describes techniques for applying under bump metallization (UBM) for solder bump interconnections on interconnection substrates. The UBM of the invention comprises a Cu, Cu/Cr, Cr multilayer structure. Problems in etching the Cu/Cr layer are overcome using a high pH etchant containing a copper complexing ingredient to prevent passivation of the copper constituent by the chromium etchant solution. With the availability of this etchant the UBM multilayer can be formed using subtractive techniques.

Abstract: The specification describes a MCM IC package with improved RF grounding. The package has at least one RF IC chip bonded to an interconnect substrate and the substrate is interconnected to an intermediate printed wiring board (IPWB). The IPWB is interconnected in turn to a system printed wiring board (SPWB). The RF IC chip is metallized on the backside, and is flip chip bonded directly to the SPWB thereby eliminating two intermediate interconnections and reducing the impedance of the interconnection between the RF chip and the SWBP.

Abstract: A method of connecting arrays of optical wavepaths is described employing externally located connector pads. After optically aligning the arrays to be connected, the connector pads are bonded to the arrays and then to each other. In the preferred embodiments, the pads, which typically are thin silicon wafers, and the arrays are metalized and then soldered together. The use of connector pads to connect arrays of optical transmission paths results in sturdy, stable connections. The technique is fast, simple and inexpensive, and is consistent with current alignment procedures. By using solder to secure the pads to the arrays and to each other, connections can be undone and then redone. Inasmuch as all connections are external to the optical paths, there is no deterioration of the optical connections with time.

Abstract: Cleaning of a micromimiature high-density flip-chip assembly is carried out by spinning the assembly while applying cleaning fluid to a central portion of the assembly. Confinement of the cleaning fluid to a critical interconnection space of the assembly is ensured by a centrally apertured cover that resiliently engages the top of the assembly. During spinning, cleaning fluid is introduced through the aperture in the cover and is directed into and confined to flow radially in the interconnection space.

Abstract: A novel packaging of semiconductor elements, such as MCM tiles, with a variety of printed circuit or wired boards (PWB), the packages occupying a small size, at least in the vertical direction, relative to prior art OMPAC devices. The MCM tile includes an interconnection substrate with peripheral metallizations and at least one chip or integrated circuit (IC) mounted on the substrate by solder reflow or conductive adhesive technology. The PWB which may be a single level or a multilevel, is provided with an aperture for accommodation of at least one chip therein. Depending on the type of interconnection between the substrate and the PWB, the aperture may be larger than the substrate of the MCM tile for wire bonding interconnection or smaller than the substrate for solder reflow or conductive adhesive interconnection. In the wire bonding case, the MCM tile is positioned within the aperture resting on the surface of the PWB or of a structural member or of a heat sink which encloses one end of the aperture.

Abstract: Described is a novel packaging of MCM tiles without wire-bond interconnections and in a total thickness which is reduced relative to conventional MCM packaging. The MCM tile includes a substrate with a plurality of peripheral metallizations and at least one chip flip-chip mounted on the substrate. The PWB is provided with an aperture which is smaller than the size of the silicon substrate but larger than the outside dimensions of the mounted chips. The substrate is positioned on the PWB so that its ends overlap areas of the PWB adjacent the aperture and the chips fit into the aperture. Peripheral metallizations on the substrate are interconnected to metallizations on the PWB by either solder reflow technology or conductive adhesive technology.

Abstract: A multichip module is assembled using flip-chip bonding technology, a stencil printable solder paste and standard surface mount equipment for interconnecting signaling input/output contact pads on devices within such a multichip module. The disclosed assembly process makes the heretofore difficult and expensive flip chip bonding technique achievable at low cost. The flip chip bonding technique is simplified by use of a solder paste which includes desirable reflow alignment, fluxing and printability characteristics. These desirable characteristics allow the assembly process to be further economically achieved by permitting the use of standard surface mount equipment in the process. High volume production of standard inexpensive modules are thus possible through this process while also achieving the advantage of high density interconnections afforded through the flip-chip bonding technology.

Abstract: A process for fabricating devices is disclosed. Numerous devices are formed on a substrate. The substrate is then placed on an adhesive tape mounted on a dicing ring. The devices are then separated into individual chips by dicing the substrate. Prior to dicing, the substrate is coated with a material that is relatively insoluble in water. After the substrate is diced, the coating is removed by rinsing the substrate with an organic solvent in which the material is substantially soluble. The organic solvent dissolves the coating but does not dissolve the adhesive on the tape or otherwise adversely effect the adhesion between the tape and the substrate.

Abstract: The bonding pads (18) of a semiconductor chip (12) each may be provided with a solder bump (36) by first screen printing a pattern of solder paste (36) on a heat-resistant, non-wettable surface (24). The chip (12) is then placed on the surface (24) so each bonding pad (18) contacts a portion of the solder paste pattern (36). The solder paste is then reflowed, yielding molten solder that bonds to the bonding pads (18) of the chip, but not to the surface (24). After reflow, the chip, with its now-bumped pads, is removed from the surface for subsequent soldering to a wettable substrate.

Abstract: An electronic device, such as an integrated circuit chip or a multichip module, is held in place overlying a circuit board, with which it is thermal expansion mismatched, by three or more localized rigid support elements. The bottom surface of the chip is bonded to the top surface of preferably only one of these support elements and can laterally slide along the top surfaces of the others in response to heating and cooling during electrical operations of the electronic device. In addition, the electronic device is encapsulated in a soft gel that is held in place by a rigid plastic half-shell cover that is epoxy-bonded in place along its perimeter (edge).

Abstract: The quality of soldering produced on devices such as printed circuit boards and multichip modules is significantly improved through use of a specific size distribution of solder particles. In particular, the solder includes a vehicle and solder particles of specific size. In general, an appropriate distribution of both large and small particles should be employed. Through this expedient short circuits and soldering defects in fine line devices are reduced.

Abstract: A solder paste is composed of a vehicle (or flux) system and a mixture of at least two solder powders. One component of this mixture is a eutectic or near-eutectic Sn/Pb alloy powder, while the other component comprises powders selected from at least one elemental metal powder or at least one solder alloy powder or at least one elemental metal powder and at least one solder alloy powder. Said other component is a powder or combination of powders each of which has a liquidus temperature which is lower by at least 5 degrees Centigrade (.degree.C.) than the solidus temperature of said eutectic or near-eutectic Sn/Pb alloy powder or a solidus temperature which is higher by at least 5.degree. C. than the liquidus temperature of said eutectic or near-eutectic Sn/Pb alloy powder. The eutectic or near-eutectic Sn/Pb powder makes up from 5 to 95 weight percent of the total powder mixture. Alternatively, not all powders which comprise the second component need to obey this rule so long as at least 30% by wt.

Abstract: Described are a process for soldering at least one component having solder bumps to a substrate and a process for forming solder bumps on metal pads of an element, such as an IC package or substrate or both. The bumps are formed by stencil printing solder paste deposits on the metal pads, heating the solder paste deposits to reflow temperature of the solder in the solder paste deposits, and allowing the molten solder in each deposit to coalesce and during subsequent cooling solidify forming the bumps on the metal pads.

Abstract: A solder paste that is useful in applications such as surface mounting of components on printed circuit boards has been found. After soldering, the residue requires no cleaning. The achievement of these desirable properties is accomplished by employing a solder flux vehicle including a three component residue modifier.

Abstract: A solder flux that is useful in applications such as surface mounting of components on printed circuit boards has been found. After soldering, the residue from the flux is either removable by water cleaning or requires no cleaning at all. The achievement of these desirable properties is accomplished by employing a solder flux vehicle including a removing agent, a low vapor pressure component, a high temperature component, and a rheological properties promoter.

Abstract: Soldering is performed and the residues associated with the soldering process are removed through the use of a specific process. Components such as two integrated circuits or an integrated circuit and mounting board are initially tacked by compression bonding or through the use of adhesives. Flux is introduced, and the components to be soldered are brought to reflow temperature. The flux is chosen so that upon reflow and subsequent cooling to a temperature of 100.degree. C., or lower, the flux remains in liquid state. The flux is then easily removed by cleaning with a miscible liquid that is subsequently removed through processes such as spinning and evaporation.

Abstract: An optical fiber connector pair is provided, which includes a plug assembly and a receptacle. An optical connection can be repeatedly made and broken by insertion and withdrawal, repectively, of the plug assembly relative to the receptacle. The final alignment of the mating fiber ends is provided by a pair of silicon blocks, each having a guiding groove formed in one surface. One block is included in the receptacle, and the other block is included in the plug assembly. One fiber end is affixed in each groove. The act of inserting the plug assembly in the receptacle brings the grooved surfaces together such that each fiber is captured by the opposing groove.

Abstract: Paints and coatings involving semiconducting pigments such as titanium dioxide generally degrade because of oxidation of the binder by reactants that are photochemically produced on the pigment surface, and because of direct binder oxidation by charges that are photogenerated in the pigment. In titanium dioxide, this interaction is substantially reduced by avoiding reduced species and by introducing into the titanium dioxide trap states where photogenerated electron-hole pairs recombine by processes such as prolonged milling. Through these expedients, a substantial increase in the stability of the pigment containing composition is obtained.

Abstract: A fiber optical end connector is disclosed, comprising a grooved base member having mounted thereupon a grooved silicon block, and means for holding optical fibers in the grooves on the base member and on the silicon block.

Abstract: An m-input/n-output (e.g., 2.times.2) optical fiber switch is disclosed which alters the location of the fibers by the application of an external force. Illustratively, the switch uses a housing with a diamond-shaped opening extending therethrough, with pairs of optical fibers positioned in orthogonally located V-grooves. Upon the application of an external force, the fibers are moved into the remaining, vacant V-grooves formed by the diamond-shaped opening. In a preferred embodiment, a (2.times.2) switch is magnetically activated.