International Business Machines Corporation

Gerald S Andris

John P Gauci

John F Harmuth

Yves Darves-Bornoz

A degradation resistant nozzle for a screening, extrusion or similar processes has a tip surface formed by one or more rods of a material having an increased hardness relative to the body portion of the nozzle. The rods are preferably of circular cross-section and formed of tungsten carbide. The rods are removably attached in preferably circular grooves in the tip of the nozzle body. The removability of the rods facilitates reworking of the nozzle when wear occurs since new rods can quickly and inexpensively be substituted. The degradation resistant nozzle also decreases wear and scoring of stencils used in screening processes and thus increases the useful life thereof.

Carbide rod screening nozzles

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 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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Poughkeepsie, NY, United States of America

Gerald S Andris