Abstract: This article details the entire process of patterning an L-P2106 photosensitive resist ink on an ITO layer of an LCD. At the same time, the mechanism, process parameters and quality assurance are also discussed.

Keywords: pre-drying, screen printing, exposure, image dots Key words: Pre-dry, screen printing, exposure, developing point

1 Introduction

The LCD is an extremely important member of the optoelectronic display group, and the manufacture of the ITO layer in the LCD is an important component. L-P2106 photosensitive resist ink starts its mask for ITO layer etching with its high resolution and good corrosion resistance and excellent price ratio. After several years of promotion, the number of application manufacturers has increased, and the linewidth between the two mil lines has become popular. A considerable number of manufacturers have manufactured 1mil lines and linewidths, and recently undergone adjustment of process conditions and transformation of the environment. The line width between 1⁄2 mil and 1⁄3 mil has been reported. It seems that there is a broad space for the development of L-P2106.

2, L-P2106 photosensitive resist ink

2.1 The main principle and imaging principle of L-P2106 photosensitive resist ink:

1) Main body: Alkali-soluble unsaturated resin 2) Photoreceptor: photoinitiator and auxiliary agent 3) Diluent: Low-toxicity organic solvent or monomer is selected, and liquid aliphatic saturated carboxylic acid ester is the reaction diluent.
4) Filler: Mainly based on talcum powder 5) Pigment:
6) Others: defoamers, leveling agents, thixotropic agents, etc.

2.2 Selection of main ingredients:

First of all, we use the alkali-soluble unsaturated tree finger to select a low-toxic, low-taste reactive diluent, so that no waste is produced in the production of ink. The main body of the ink we use maleic anhydride copolymer as a skeleton resin, unsaturated compounds give its photographic properties; carboxyl groups give its base water solubility: with monomers and solvents, diluents, inorganic fillers to adjust the ink viscosity and thixotropy. The photoinitiator system used is the same as the world's advanced dry film resist for PCB fabrication without filler.

2.3 The basic principle of the reaction:

The modified skeletal tree finger, diluent, photoinitiator, and auxiliaries constitute a complete photographic system. This body generates reactive free radicals under UV light, and undergoes polymerization and cross-linking. The transparent area (photosensitive area) of the film is insoluble in the developer (0.8-1.2% Na2CO3 for the developer) but not in the transparent area (the unsensitized part is not irradiated with UV light), so no polymerization or cross-linking occurs and the developer dissolves. Then wash away the excess alkali-soluble residual ink with running water to show the resist pattern. The above process is performed after the ink is formed. The principle of film formation is: because the liquid aliphatic saturated carboxylic acid ester is used as a diluent for the reaction, it is composed of a host tree finger, a photoinitiator and an auxiliary agent, and is characterized by being liquid at normal temperature and not volatile. After heating to 80~90°C, the solvent begins to volatilize, and after a certain time, it is formed as a mask to be exposed.

3, L-P2106 photosensitive resist ink as a mask to create a simple process of ITO graphics.

... coating → pre-drying → exposure → development → washing → post-curing → etching → removing film → cleaning → drying...

3.1 Coating:

3.1.1 Ink agitation: can use manual stirring and vibration stirring, but preferred mechanical stirring, stirring in one direction, can not mix both sides of positive and negative mixing, to prevent the creation of air bubbles. Ink agitation should not be less than 20 minutes, after stirring for half an hour and then use.

3.1.2 Roller coating: It is currently the best coating method. It is characterized by its high speed and good quality. (The uniform coating is especially suitable for continuous operation and mass production, but it needs to invest in a roll coater).

3.1.3 Screen Printing: This is the most common coating method

1) Selection of mesh: nylon mesh with a small coefficient of friction, smoothness, and good black penetration should be selected.

2) The number of screen meshes: 200-250 mesh. This mesh can obtain 5-8m (dry) ink layer thickness. The reference value under the general conditions, the thickness of the solid content with the ink, the screen thickness, the hardness of the scratcher and the angle between the scratch and the substrate, running speed and so on.
The ink thickness can be roughly calculated by the following formula: Ft·X%·S
Ft: Mesh thickness; X% as coefficient; S: Solids content.
The thickness of ink leaking on the surface of the plate through the mesh is actually less than Ft, so it should be multiplied by a factor.

3) Most of the SMEs in screen printing are mostly manual. There are many drawbacks to manual operation:
First, manual operators have been working for a long time to reduce the pressure, so that the amount of ink leakage and thickness decrease;
The second is the poor accuracy of the equipment, which affects the evenness of the ink on the surface of the board. Therefore, mechanical screen printing is recommended.