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Date: | Mon, 24 Feb 97 03:04:36 UT |
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There are three basic types of printers on the market.
- Flood Systems -
Have reflectors as large as the exposure frame that contain the lamp. The
reflectors are made from a number of flat facets of aluminum that are mirror,
brush, or dimple finish. The lamps are mercury capillary, or medium pressure
arc. These systems produce soft illumination. They are the least sensitive to
dust and debris but are limited in resolution, are very sensitive to vacuum
contact and have a significant difference in performance across the exposure
plane. This is due to the differences from the center compared with the
reverse light angles caused by the side reflectors. Capillary lamps have from
10 - 15k exposures life.
- Collimated Systems -
Have high pressure short arc lamps in an elliptical reflector that refocuses
the lamp on an optical integrator, the rays are then bounced from a parabolic
collimating mirror before striking the exposure plane. The system has the
least sensitivity to out of contact exposures. The tight optical angles tends
to reproduce flaws in the glass, and the artwork. There is also a high
sensitivity to dust and debris. These systems are the more costly to purchase,
and have a higher operating cost due to lamp cost and life, power consumption,
air conditioning load and the required cleanliness of the environment. Yields
are often a trade of shorts for opens. Lamps have a 750h to 1000h life, there
is an explosion possibility if lamps are run too long.
- Point Source Systems -
Have a compact optical system, lamp plus reflector that is typically 25 cm
square. These systems use medium pressure additive lamps that can be
manufactured with a spectrum which optimizes the resolution of the
photoresist. They provide a compromise between flood and collimation in
optical sharpness. On a scale of 1 to 10 with collimation being 1 and flood
systems rating a 10, the optical sharpness of the point source is 3. The
higher intensity and favorable spectrum enhance the resolution. As a result of
the increased resolution over flood systems in combination with a reduced
sensitivity to flaws and debris of collimated system, the point system tends
to produce at higher yields. Lamps are the least costly and have a 1000 -
2500 hour life.
Bert Ohlig
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From: [log in to unmask]
Sent: Thursday, February 20, 1997 12:47 AM
To: [log in to unmask]
Subject: Collimation or not?
\0
TO: I4235700 IBMMAIL IBM Mail exchange
FROM: DWALLACE EX2 D.Wallace - Process Control Mngr
Dunsdale
DATE: 20 February 1997
SUBJECT: Collimation or not?
I am interested in some user input regarding collimated light
source exposure units for imaging multilayer innerlayers.
Currently, we use ORC (Japan) point light source units in
combination with a glass to glass vacuumed print frame and we are
able to achieve very acceptable yields on 100 micron track / gap
technology. We wish to improve this capability down to 50 micron
track / gap. Is collimation the only practical way of achieving
this? Are there any other benefits in using this type of light
source? What, if any, are the drawbacks?
Thanks in advance for any imput.
David H Wallace Process Control Manager Exacta Circuits Limited.
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