International Business Machines Corporation

John P Gauci

Gerald S Andris

David Clifford Long

Harry David Cox

Thong N Nguyen

John R Lankard, Jr

Robert L Baan

Krystyna Waleria Semkow

Renee L Weisman

Paul F Findeis

John F Harmuth

Thomas A Kline

A method for mounting a film, used to fabricate a mask for use in screening an electronic device, to a common carrier frame. The common carrier frame has an outer edge along an outer periphery and an opening in a central portion of the frame. The method includes applying external pressure to the frame outer edge to compress the frame inward and reduce the opening, securing a film to the frame, the film covering the frame opening, and releasing the pressure on the frame to expand the opening and place the film in tension.

Common carrier

A process for reworking of PGA chip carriers where one or more I/O pins is unplated. The process includes electrolytically etching the I/O pins which removes any corrosion product from the unplated I/O pins and removes the top gold layer from the remaining I/O pins. The etchant includes a metal-providing compound selected from the group consisting of a silver salt, copper cyanide, silver cyanide, gold cyanide or mixtures thereof, at a concentration in the range from about 2.7 to about 4.1 g/l as metal; potassium or sodium carbonate at a concentration in the range from about 10 to about 100 g/l; and potassium or sodium cyanide at a concentration in the range from about 29 to about 35 g/l.

Process of reworking pin grid array chip carriers

In the manufacture of multi-layer ceramic interconnect structures, a greensheet is perforated with small holes and positioned on the support fixture of a screening machine. Then a planar surface of a screening mask is positioned in relation to the greensheet for producing the circuit pattern. Then the discharge end of a paste nozzle is positioned in relation to the opposite planer surface of the mask for injecting pressurized conductive paste through the nozzle into the mask. A normal force is applied to the nozzle toward the mask to maintain the discharge end of the nozzle with a clearance of 1 to 2 mils from the mask as the nozzle traverses the mask, injecting the conductive paste to extrude the circuit pattern on the greensheet and fill the perforations to produce vias to provide electrical connections between the layers produced. The force is adjusted dependent upon the pressure of the paste being injected into the mask to maintain the 1 to 2 mil clearance. Multiple layers of patterned greensheets are stacked and sintered under pressure and high temperature to produce the multi-layer ceramic interconnect structure.

Manufacture of a multi-layer interconnect structure

Apparatus for manufacture of multi-layer ceramic interconnect structures

A multilayer ceramic substrate with an internal cavity extending from the top to the bottom surface of the substrate is produced using an insert material which fits within a cavity defined by aligned openings of individual ceramic sheets in a multilayer stack. The multilayer stack of ceramic sheets, together with the insert, is press-molded together with the insert serving as an internal mold that maintains the internal dimensions of the cavity. The insert is slightly larger in its top to bottom dimension than the multilayer stack and is driven into a compressible material underlying the multilayer stack during the pressing operation. The insert prevents the ceramic from flowing upwards into the center of the cavity during the pressing operation. In addition, the insert embeds electrically conductive pads located at various levels inside the cavity on individual ceramic sheets in the multilayer stack into the top surfaces of the ceramic sheets. After molding, the insert and the compressible material are removed from the multilayer structure. The invention has a particular application for forming multilayer ceramic structures that are connected to an integrated circuit chip and heat sink combination that will be positioned inside the cavity of the ceramic structure.

Process for forming open-centered multilayer ceramic substrates

A shock absorber pad for absorbing shock caused by separation of a perforated sheet mask from a surface on which a pattern of a screened medium has been formed by forcing a viscous material through the mask which includes a plurality of protuberant features which have a separation determined in accordance with a nominal viscosity of the screened medium and a transverse feature dimension based on characteristic stand-off spacing or mask feature size increases pattern quality and extends mask life. Hollow pattern features also improve pattern quality by reducing pad contact area with the mask during separation while allowing the pad features to span mask features. Methodology of shock absorber pad design and adjustment of screened medium viscosity to pad feature spacing are included.

Mask shock absorber pad

An apparatus and method for screening a pattern of material onto a surface including detection of the instant of separation of the mask from the surface after screening. Particularly as applied to a process for making a multi-layer ceramic device with an automated apparatus, the screening process is speeded by initiating high speed movement immediately when the separation of the mask from the surface is complete. In a preferred embodiment, a shock absorber is used to limit the rate of change of motion of the mask and a sensor is placed directly on a portion of the shock absorber structure. Noise reduction is accomplished through differential sensing and thresholding to improve detection.

Thick film mask separation detection system

An apparatus and a method is disclosed for providing a controlled separation of a structure that has been screened from the screening mask. A dampener pad floats with the mask as the screened structure is being separated from the mask. The mask is held in place by the dampener pad while the structure completely separates from the mask. The dampener pad assembly, then, in a controlled manner, brings the mask back to the original position, and the mask is then ready for the next screening operation.

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Putnam Valley, NY, United States of America

John P Gauci