| 摘要 |
<p>A square drilled flat ceramic substrate is placed in a trough in a worktable and retained by three fixed pins and one movable pin. Below the trough is a drainage gap and a vacuum chamber. The vacuum pipe is connected via a valve and a larger vacuum chamber to a vacuum pump. - The required vacuum is maintained by a servo loop consisting of two detectors, connected to the two vacuum chambers and a pump control circuit. The paste is skimmed over a sleeve and drawn through the holes in the substrate by the vacuum. The whole process is controlled by a general control circuit which switches power to the skimmer, sieve and pump. (0/2) GBAB- GB2143473 B A screen printing process which comprises the steps of applying an electrically conductive paste through a screen (2) and by means of a movable squeegee (3) to a surface of a substrate (23) provided with at least one hole (24) extending between the surface and another surface if the substrate (23) whilst exerting an underpressure on the other surface so as to coat at least part of the inner wall of the hole (24) with paste, wherein the underpressure is maintained substantially constant and equal to a value between 10 gr/cm2 and 200 gr/cm2.a USAB- US4959246 A The screen printing process comprises the steps of: applying an electrically conductive paste through a screen and by a movable squeege to a surface of a substrate provided with at least one hole extending between the surface and another surface of the substrate and exerting an underpressure on the other surface to coat at least part of the inner wall of the hole with the paste. - The underpressure is substantially constant and equal to a first value between limits of 10 gr/cm2 and 200 gr/cm2, in that the underpressure is obtained from a vacuum vat and in that the underpressure is realised in a vacuum chamber located next to the substrate and communicating with the vacuum vat, the vacuum vat having a volume which is relatively large with respect to that of the vacuum chamber. (5pp)</p> |
