Delco Electronics Corporation

Delphi Technologies, Inc.

James Edward Walsh

Frans Peter Lautzenhiser

John Karl Isenberg

Carl William Berlin

Adam Wade Schubring

An improved method of making a multiple print thick film circuit wherein the alignment between successive conductor print steps is both optically inspectable and electrically testable. The first of two or more successive conductor print layers includes a pair of adjacent alignment features with a non-conductive gap therebetween, and the successive conductor print layer includes a pair of identical alignment features which are printed directly on top of the alignment feature pair of the first print layer. When the successive print layer is properly aligned with the first print layer, the non-conductive gap between the alignment features of the first print layer will be preserved, and test probes brought into contact with the features or associated probe pads will reveal a high or open-circuit impedance therebetween. If the successive print layer is mis-aligned relative to the first print layer, one or more of its alignment feature segments or surfaces will bridge the non-conductive gap between the alignment features of the first print layer, and test probes brought into contact with the features or associated probe pads will reveal a low or short-circuit impedance therebetween. Additionally or alternatively, the gap between adjacent alignment features may be optically inspected.

Print alignment method for multiple print thick film circuits

An improved method of manufacturing thick film circuits that effectively eliminates the trade-off between thickness and definition, permitting dielectric layers of increased thickness with no pin-holes, and at the same time, more precise definition of dielectric features, such as via openings and solder stops. The method utilizes a dielectric material that can be co-fired with an underlying conductor, and preferably, that remains porous after firing. A layer of the dielectric material (FDL) is printed atop a dried but not yet fired conductor of the first circuit layer, and then co-fired with the conductor. Spreading of the FDL prior to firing is minimized due to the porosity of the dried but unfired conductor, which absorbs solvent from the FDL. The FDL can be printed in a ring, enclosing a portion of the underlying conductor to form a via definition ring, or VDR. After the FDL and conductor have been co-fired, a relatively thick cover layer of conventional dielectric material is printed over the first circuit layer, partially over-lapping the fired VDR. Again, spreading of the cover layer of dielectric is minimized, this time due to the porosity of the fired VDR, which absorbs solvent from the cover layer dielectric. The cover layer dielectric is then fired, and a second cover layer of conventional dielectric is printed atop the first cover layer to achieve the desired overall dielectric thickness. Spreading of the second cover layer is also inhibited by the fired VDR, resulting in a via with greatly improved definition compared to previously known processes. Alternatively, the FDL can be printed atop a dried but un-fired conductor and then co-fired with the conductor to form a solder stop with significantly improved feature definition. As with the via, the improved definition occurs because the porous un-fired conductor inhibits spreading of the FDL.

Method of manufacturing a thick film circuit with improved dielectric

An improved method of manufacturing multi-layer thick film circuits that effectively eliminates the trade-off between thickness and definition, permitting dielectric layers of increased thickness with no pin-holes, and at the same time, more precise definition of dielectric features, such as via openings and solder stops. The dielectric features are precisely defined by an initial thin layer of dielectric material, referred to as a feature definition print, or FDP. After the FDP has been dried but not yet fired, a via can be formed by printing a comparatively thick cover layer of dielectric, over-lapping the edges of the FDP. Due to the porous nature of the dried but not fired FDP, it absorbs solvent from the dielectric cover layer, which inhibits the spreading of the dielectric cover layer. The FDP is then co-fired with the first dielectric layer, and a second dielectric layer may be provided atop the fired first layer to further increase the overall dielectric thickness, if so desired. This results in a thicker dielectric layer for the same number of successive printing steps, and at the same time, smaller dielectric features. The thicker dielectric layer provides improved isolation between circuit layers, and the smaller dielectric features increase the available surface area for conductors and components on the upper dielectric layer. Additionally, process robustness is improved, since there is less fine tuning and batch-to-batch variation when used in high volume production.

Method of manufacture for a thick film multi-layer circuit

A screen printing device for screen printing a thick film ink through a screen so as to form a highly-defined thick film on a surface of a microelectronics circuit. The screen printing device achieves the above by bypassing excess ink that would otherwise accumulate ahead of the squeegee device, thereby limiting the pressure lead length ahead of the device during the screen printing process. As such, the screen is able to form an adequate seal with the surface of the substrate to prevent ink from bleeding out under the screen, i.e., between the screen and substrate. The result is a well-defined thick film on the substrate, and avoids the necessity of stopping the printing operation in order to remove ink from the lower surface of the screen. The screen printing device enables a method by which well-defined films can be readily deposited at high throughput levels, without necessitating additional procedures, equipment and techniques that might otherwise further complicate the printing process.

Growing community of inventors

W. Lafayette, IN, United States of America

James Edward Walsh