High-speed, fully automatic screen printer for substrates, wafers and panels for solar cell production

Microelectronics International

ISSN: 1356-5362

Article publication date: 1 April 2000




(2000), "High-speed, fully automatic screen printer for substrates, wafers and panels for solar cell production", Microelectronics International, Vol. 17 No. 1. https://doi.org/10.1108/mi.2000.21817aad.013



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

High-speed, fully automatic screen printer for substrates, wafers and panels for solar cell production

High-speed, fully automatic screen printer for substrates, wafers and panels for solar cell production

Keywords: Screen printer, Ekra

A short tact time of three seconds, very high flexibility with minimal changeover time and ease-of-use are reported as the outstanding characteristics of the new screen printer EKRA Microtronic 8-DT. Its application is targeted at ceramic substrates (for hybrid manufacturing), silicon wafers, PCBs and panels for the production of solar cells. The printer can be easily adapted to a wide range of different formats and sizes of substrates. The patented and well-proven EVA (EKRA Vision Alignment) system with its highly precise XY gantry system, featuring glass-scale reading and closed-loop control, is fitted as standard. The EVA performs with an exceptional resolution of þ1 micron, providing an accurate alignment of the print screen to the fixed substrate in the printing cell.

The new printer features two independent print tables that can be alternately loaded and unloaded with substrates to drastically reduce handling and imaging time. Therefore, the printer cycle time is extremely short. With a squeegee stroke time of one second and a positioning based on two fiducials, the printer achieves a superior short tact time of only three seconds This provides the opportunity for 1,200 complete print cycles per hour and high throughput gains.

The alignment system uses a CCD camera that is freely programmable over the entire printing area. The positions of the index markings can be provided both by the input of the XY values or by a teach-in procedure. When a switch-over to other substrate formats is needed during production, no mechanical modifications are necessary since the camera can be easily moved allowing rectangular, semi-rectangular or rounded substrates to be processed. Printed substrates can be easily transferred back into the positioning system via the set-up menu to provide an accurate optical verification of the print utilizing the index markings/fiducials or the edges of the print cell. Print-offsets can be readily corrected without any difficulty by software function. Because of this valuable feature it is not necessary to dismount the entire printing cell and verifying by a separate, external measurement. Using a vacuum check the machine detects automatically when there is no substrate in printing position.

Screen frames with outer dimensions of 600 x 600mm (23.6 x 23.6 inches) can be used, whereas the maximum print area is specified at 203 x 305mm (8 x 12 inches). Substrates up to a thickness of 4mm (0.16-in) can be used. The repeatability is þ 12.5 micron (at six sigma).

The squeegee pressure is in the range of 25 to 250N and is controlled by pneumatic technology, and the squeegee speed is programmable from ten to 300mm/seconds. Also, the speed and distance of separation are programmable, as is the integrated screen lift feature. All print parameters of every product can be saved and are easily accessible if needed again. The production changeover to previously processed substrate is possible within five minutes. When a new print program has to be generated, the changeover does not take more than 15 minutes. The high flexibility enables the EKRA screen printer Microtronic 8-DT to be seamlessly integrated into almost every kind of manufacturing environment.

For further details: Tel: +49 7143 88440; E-mail: marketing@ekra.com

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