Abstract:
Certain organic polymeric materials are capable of reversibly accepting or donating electrons from a reducing entity. The redox sites in the polymer accept electrons and, as a result, a change in the properties of the polymer occurs. This change is useful in modifying or etching the polymeric material. The material can be modified by incorporation of metallic seeds into the material at a controlled depth. The seeds are incorporated by interaction of cations of the metals with the redox sites in the polymer, which cause the reduction of the cations to form the neutral metallic seeds. Subsequent exposure of the polymeric material containing the seeds to an electroless bath causes further deposition of metal having the desirable characteristic of good adhesion to the polymeric material. Etching of the polymeric material can be carried out as a result of an increase in solubility of the polymer in aprotic solvents when its redox sites have accepted electrons. The increased solubility allows openings to be etched in certain areas of the polymeric material that have been reduced, leaving other areas unchanged.
Abstract:
A multi-chip module having very high density interconnect structures and a technique for making it, where all of the chips have their active device surfaces in a common plane. The chips are placed face down on an adjacent adhesive layer located on a substrate, which is preferably a flexible material. A conformal material is deposited over the backsides of the chips and in the spaces between the chips. A ground plane or metallic shield can then be formed over the conformal layer, if desired. The structure is then turned over and the glass layer on which the substrate is located is removed. Access vias are made through the substrate to the chip I/O's, and metallization provided to the chips. Interconnect metallization is then provided to complete the multi-chip module. In one embodiment, the substrate on which the chips are first supported is the first level of insulation above the active device surfaces of the chips and also ensures that the active device surfaces are in a common plane.
Abstract:
Certain organic polymeric materials are capable of reversibly accepting or donating electrons from a reducing entity. The redox sites in the polymer accept electrons and, as a result, a change in the properties of the polymer occurs. This change is useful in modifying or etching the polymeric material The material can be modified by incorporation of metallic seeds into the material at a controlled depth. The seeds are incorporated by interaction of cations of the metals with the redox sites in the polymer, which cause the reduction of the cations to form the neutral metallic seeds. Subsequent exposure of the polymeric material containing the seeds to an electroless bath causes further deposition of metal having the desirable characteristic of good adhesion to the polymeric material. Etching of the polymeric material can be carried out as a result of an increase in solubility of the polymer in aprotic solvents when its redox sites have accepted electrons. The increased solubility allows openings to be etched in certain areas of the polymeric material that have been reduced, leaving other areas unchanged.
Abstract:
An electromagnetic printhead is fabricated with a common flux returning backplate and an array of writing elements extending from the common backplate. The writing elements consist of large pedestals and small pedestals. The placement of the large pedestals provides addressability resolution; the small pedestals provide imaging resolution. The large pedestals accept electromagnetic flux from addressing conductors and transfer the flux through the respectively related small pedestals to an image receptor. There are several fabrication techniques which are eased by the separation of addressability resolution and imaging resolution, primarily because the wide separation of the large pedestals required for the addressing conductors mandate relatively massive removal of material and thus suggest relatively low precision machining techniques. The imaging resolution requires both high spacial precision and accurate dimension control, normally achievable by relatively high precision techniques. With the functions addressability resolution and imaging resolution functions separately provided, the best and most economical techniques may be used for each. The magnetic flux path for recording may be either vertical or in-plane, and the flux return may be common via the relatively low reluctance path provided by very large area paths through the mass of nonferromagnetic material to the common flux returning backplate. This simplified printhead lends itself to the use of standard flexible circuit fabrication techniques for the addressing conductors.
Abstract:
Disclosed is a reworkable circuit .package formed by controlled collapse chip connection ("C4") bonding of integrated circuit chips to circuit cards and boards, and direct chip attachment ("DCA") where an encapsulant is disposed under the chip. The encapsulant offers protection of the C4 connections and a thermal expansion matched to that of the C4 joints. However, most encapsulants interfere with reworkability. The disclosed circuit package overcomes this problem by the provision of a passivating layer of Parylene is reworkable, dry processable, uniformly depositable by vapor phase deposition, forming thin films on facing surfaces at the 3-5 micron film thickness corresponding to the C4 lift-off distance.
Abstract:
The present invention comprises the use of a copper/nickel containing alloy composition or application of a protective nickel alloy coating to copper current-carrying leads to prevent electrolytic migration between tape automated bonding (TAB) package leads.
Abstract:
A heat exchanger for cooling an array of electric circuit chips disposed on a common substrate is formed as a flexible sheet of thermally conducting material with upstanding fins for transference of heat from the chips to a coolant flowing through the fins. Pin fins may be employed with air coolant. The sheet may be provided with corrugations set between sites of the chips for improved flexibility to accommodate individual orientations of the chips. The sheet is sufficiently large to cover an array of chips and is thermally joined, as by use of a thermally conductive grease, to the chips. The sheet hermetically seals the chips from contamination by the coolant. For liquid coolant, the heat exchanger may be fabricated of copper with a nickel coating, wherein the copper provides the heat conduction and the nickel protects the copper from a corrosive coolant such as water. In one embodiment of the heat exchanger, the fin thickness, the fin spacing and the sheet thickness are all approximately equal, a typical sheet thickness being approximately two mils. Another embodiment uses air cooling, and uses metal pin fins bonded to a metal sheet which is moderately thin and flexible. Transverse motion between the sheet and the array of chips is introduced concurrently with the application of pressure between the sheet and the chips to reduce the thickness of the layers of grease between the chips and the sheet, thereby to improve thermal conductivity between the heat exchanger and each of the chips.
Abstract:
A method for fluxlessly joining members having relatively low melting materials is provided. The members to be joined are exposed to ion beam radiation of sufficient intensity and a time sufficient to cause cleaning of the low melting materials after cooling. The members are then placed into juxtaposition with each other and again exposed to ion beam radiation of an intensity and for a time sufficient to cause reflow of the low melting materials which upon cooling joins said members.
Abstract:
Methods and apparatus are set forth for passively and precisely aligning pairs of objects, in particular, microelectronic components such as semiconductor lasers and fibers, utilizing fiducial marks. Additionally, methods and apparatus are set forth for combining passive and active alignment techniques where high degrees of alignment precision are required. Still further, techniques are described for fixing prealigned objects, independent of how the objects are prealigned, to a mounting surface in a manner that maintains the relative (aligned) position of the objects. Further yet, in order to help minimize manufacturing costs with respect to production of, for example, microelectronic assemblies, batch processing techniques are described which utilize the novel alignment procedures contemplated by the invention.
Abstract:
The superior thermal conductivity of immersion cooling combined with the service convenience of conduction cooling is provided through the use of unitary thermal transfer replaceable units positioned beneath a refrigeration source. Each unit contains electronic devices in a thermal transfer fluid. The unit construction permits replaceability in service without exposing a central fluid reservoir or opening a refrigerator.