General description

Failure of thickness of any printed layers of glass substrates in the printing process can be caused by non-uniform heat treatment after printing. It may be attributable to handling of glass substrates during the transfer. This session explains available solutions to the problem.

Explanation

For glass substrates, silicon substrates, and other thin works, printing using resist solutions and other various dilute solutions should be processed in the continuous production line. Then, the printing process should be followed by preliminary drying and final drying heat treatment. Depending on whether or not the thin sheet-like works are handled appropriately in the heat treatment process, printing failure can occur. This session explains how the thin sheet-like works should be handled in the transfer line to prevent possible defective print quality after heat treatment due to any inconsistent heat conduction.

(1)Explanation about production line

-Glass substrates, silicon substrates, and other thin sheet-like works should be subject to cleaning, drying, printing, preliminary drying, final printing, and other processes continuously at specific durations of tact time in the automated resist processing line and drying line.
-Thin sheet-like works loaded in the production line, especially in the case where thin sheet-like works of different thicknesses are loaded, are likely to cause uneven thickness of printed layers in the heat treatment process.

(2)Explanation about possible causes for failure thickness of printed layers

-The printing process to glass substrates involves lifting up operation of the glass substrates by metal pins for handling on the tables for both printing machine and preliminary drying.
-When glass substrates are lifted up by metal pins on the preliminary drying table, failure thickness of printed layers occurs easily around the metal pins (Fig.1).
-This failure results from incomplete preliminary drying after printing, which is explained by the fact that due to the contact of metal pins with glass substrates, the contact area of heated glass substrates with metal pins becomes locally cooled, thereby leading to lowered temperature.
-Thus, the smaller the thickness of glass substrates and silicon substrates, the more severe failure thickness of printed layer occurs around the contact area with metal pins.

(3)Solutions to possible failure thickness of printed layers

-Due to the high thermal conductivity feature, metallic parts incorporate more thermal energy from glass substrates.
-In order to minimize the incorporation of thermal energy from metal pins, such solutions are recommended that adopt the design to apply a material of lower thermal conductivity for the tips of metal pins and/or change the material of the tips of metal pins (Fig.2).