Coating processes – Vacuum utilized prior to or during coating
Patent
1983-10-24
1985-12-24
Pianalto, Bernard D.
Coating processes
Vacuum utilized prior to or during coating
4274343, 4274345, B05D 300
Patent
active
045605904
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and apparatus to apply a coating on a flat surface.
Thereby use is made of a sub-micron filtered gaseous environment for the surface during the applying thereon of this coating.
The substrates or tape, in that way provided with a coating, can be used in the micro-electronica.
In the Dutch Patent Application No. 8 103 979 of the applicant a processing system is described, in which substrates are fed through a passage of a cabin and whereby by means of media a "floating" processing of these substrates is established.
Thereby in a coating station the applying of coating on the substrate takes place, whereupon by means of whirling flows of gases excessive coating is removed.
The disadvantages of this system are the following:
1. Thin fluid coating has to be applied as a very small thickness of the applied coating layer, which is left behind on the substrate. In that way successively applying a great number of coating layers is a requirement; and
2. Due to the forces of the whirling media, acting on the applied coating layer, the surface thereof is not smooth.
The apparatus for coating application according to the invention, whereby use is made of this "floating" processing of the substrates or tapes in the cabin passage, now is characterized by having means, included therein, to enable that after the passing of the coating application section the surface of such substrates or tape is free of excessive coating.
A following positive characteristic of the apparatus is, that as seen in the direction of movement of the substrate or tape, immediately behind the coating application channel a segment wall section is included therein, which for at least part thereof is at least near parallel to the substrate or tape, as a first coating passage.
Also, that thereby before the coating supply channel a segment wall section is included therein, which for at least part thereof is at least near parallel to the substrate or tape, as a second coating passage, and under the influence of the media in the passage, acting on the substrate or tape, in this second coating passage such a coating lock is created and maintained, that coating is prevented from displacement therein with a higher speed then that of the substrate in the direction of substrate movement.
The first coating passage can also be constructed in that way such that therein a coating lock is created and maintained, which prevents the leakage of coating in a direction, which is opposite to the direction of movement of the substrates or tape.
Consequently, by metering the volume of the supplied coating per second in combination with both coating locks a desired thickness of the applied coating can be obtained.
Such a metered coating supply apparatus can in particular be used with square substrates and tapes.
With substrates, not completely filling the total cabin passage, such as in the case of most circular substrates (wafers), inevitably at least periodically a leakage of coating occurs.
In view of this, another positive structure of the apparatus according to the invention is, that immediately behind the coating application channel a vacumized discharge is located. Such a discharge channel can also function for the discharge of excessive coating.
Furthermore, as seen in the direction of movement of the substrate, the flow resistance of the coating passage defined between the coating supply channel and such a vacuum channel, positioned behind it, is considerably smaller than that of the coating passage between the coating supply chnnel and the supply channel in front of it, which functions for the urging of additional media towards the substrate.
Furthermore, coating, applied in the second coating passage, functions as a coating lock for excessive coating. This coating is displaced together with the substrate, as the first coating passage coating is urged towards the vacuum channel. In combination with the metered supply of coating per second, the passage width of both passages is predetermined and consequently the thickness of the c
Olsen Warren E.
Pianalto Bernard D.
Semmes David H.
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