L-P2106 photosensitive resist ink in the whole process of LCD graphic manufacturing (3)

The exposure time required to obtain a predetermined number of stages (optimal number of stages) can be calculated as follows (in the case of a fixed light source).

4) Calculation of exposure time:

a. Increase the number of stages: increase the number of stages required by the selected exposure coefficient multiplied by the original measurement series exposure time is the exposure time of your desired series.
For example: Exposure 16s is measured as 6 levels of normal development (temperature, concentration, time), and 8 is recommended, and 2 levels need to be added. The 2-stage coefficient was found to be 1.999, so the exposure time to obtain 8 levels is 16s×1.999=31 which is 31s.

b. Decrease the number of stages: Also select the number of steps required to reduce, and then divide the exposure time of the original measured series, which is the exposure time you need.
For example: Exposure 40s is measured as 13, and recommended as 8, according to the required number of stages to be reduced by 5, to find the coefficient of 5.61 to 5.651, so to obtain 8 levels of exposure time should be 40s ÷ 5.651 = 7s .

5.4 light energy, ink thickness, resolution:

1) Relationship between light energy and ink thickness of L-P2106 photosensitive resist ink.

2) Light energy and resolution of L-P2106 photosensitive resist ink.

Table 2 Resolution at different exposure energies (development time 22 s, film thickness 10 μm) mW/cm 2 = 5

5.5 Thin line exposure and oxygen inhibition:

We must consider the factors affecting it when making a line width of 2 mils. We only want to discuss the exposure of thin lines here. Although there are many factors involved in manufacturing a 2 mil line width, it is not possible to guarantee the sharpness of the line and the orderliness of the edges when making a 1 mil line width or less than 1 mil. This is because the retardation of O2 in the ink is a problem, which can slow down the actinic cross-linking until it is stopped, and can also make the surface sticky in severe cases. The role of O2 has two aspects:

One is the effect on the initiator, which can quench the photosensitizer in the excited state, thereby reducing the initiator's efficiency. The second is the inhibition during the polymerization process.

In order to avoid the interference of O2, the ink was photopolymerized under UV light. The experts conducted a long-term experiment and found several ways to avoid the interference of O2.

The first method, the physical method, isolates O2 from the curing system, but it is difficult to operate. However, this method is used on the dry film of the PCB manufacturing pattern. Due to the polyester film covering the dry film, the exposure is better. Excluded. However, the 0.02 mm thick polyester film refracts and scatters UV light to a slight degree, which also poses an obstacle to the production of fine lines.

The second method is to choose a good photoinitiator system in the ink formulation.

The third method is to increase the concentration of the photoinitiator, destroy the oxygen velocity of the surface, thereby causing the surface velocity to solidify, and the solidified surface can block the diffusion of oxygen. In addition, dry oil is added to the photosensitive resin, and the effect of oxygen is used to reduce the effect of oxygen.

In summary, although many methods have been devised for avoiding oxygen for photosensitive inks and have been implemented in newly manufactured inks, a certain effect is obtained in user use, but if thin lines are manufactured, first of all, the intensity of exposure should be taken into account (of course There are other conditions that are not mentioned here.)

In the exposure of ink, the intensity of light is a very large variable, as we usually use domestic exposure machine, using 4KW exposure 10s, can make the line to get a satisfactory effect, if you use 2KW exposure 20s, the line is relatively thick and thin In many cases, this is because the upper layer of the photosensitive resist ink is quickly cross-linked after being exposed to UV light, but due to the strength, UV light cannot enter the lower layer quickly. At this time, O2 is transported from the non-exposed area to the anoxic exposed area. , This is due to the difference in the concentration of the rise and fall, this time due to the extension of the time and the diffusion of light diffusion and polymerization can not be completed, and stay in the exposed area and its surroundings. This phenomenon occurs in a range of about 10-15 μm in ink thickness, so the coating must not be thick.

The ink is thick, and when the UV intensity is insufficient, the light enters the bottom layer longer, so that the intensity of the exposure and the exposure time (maintaining a certain amount of light energy) must be increased when manufacturing the thin lines, so that the dissolution of O2 is faster than diffusion into the exposure. The speed of the zone requires that the exposure process (polymerization and cross-linking completed) be completed when the oxygen in the non-exposed areas is too late to enter the exposure zone. In short, the higher the exposure intensity at the prescribed light energy, the shorter the time, and the finer the lines. Necessary guarantee.