In our production of membrane switches, panels and acrylic panels, a considerable part of them are embedded in display windows. This window is designed for the display of the LCD panel, so that the display function of the equipment can be ensured. I believe everyone is no stranger to the design of membrane panel switches. So, do you know how to design LCD panels?

Nowadays, computer-aided design and auxiliary manufacturing technology are widely used in various industries, especially in the construction, machinery, printing, and electronic industries. Among them, there are many graphics and image processing software that are widely used in mechanical drawing, printed circuit manufacturing, advertising production, graphic design, film and television post-production, etc., but there is currently no special design software for LCD panel design.

1. Characteristics LCD Panel Graphics

LCD is an extremely important member of the photoelectric display group. The LCD panel can display letters, numbers, symbols, and graphics, and has a mixed display function of text and screen. The manufacturing of the ITO layer implementation circuit in the LCD is an important part. The pattern of the ITO conductive layer has high precision requirements, such as the frame requirement of 3mm. The lines require smooth edges and no burrs. The graphics requirements are complete. In addition to the high requirements for graphic accuracy, there are many electrode leads on the panel that need to be designed. The distance between the electrode leads is O. 02mm, the minimum is 0.015mm, and after the upper and lower panels overlap, the leads on the upper and lower graphics must not overlap or cross. Therefore, CAD software for designing LCD panels must have high accuracy.

2. Applicability of LCD Panel Design Software

It is unimaginable to use the previous method of plate making to make precise graphics like LCD by hand. We must adopt or use efficient, convenient and accurate CAD technology to realize the design and production of LCD panels. The development of graphics and image processing software has solved this problem for us.

There are many graphics and image processing software, including AUTOCAD, Photoshop, Coredraw, Protel99, CAM, etc. Among them, Photoshop and Coredraw take the production of graphic images as the main function, but the accuracy is not very high. Protel99 is mainly used to design electronic circuit boards. The AUTOCAD software is extremely accurate, so it is used by people to design and manufacture LCD panels.

3. LCD Panel Design Rules

3.1 The appearance size of the LCD

(1) In principle, the external dimensions of the LCD are based on the needs of customers. When assembling, the periphery of the LCD is generally 0.2mm smaller than the frame.

(2) The size of the LCD terminal is based on customer needs. The number of terminals of the LCD should also be the same as the number of terminals of the PCB to achieve a one-to-one correspondence. When the spacing of the PCB is 1.25mm, the width of its terminal is generally best designed to be the same as the width of the PCB.

(3) The thickness of the upper polarizer and the lower polarizer of the LCD are generally the same, in the range of 0.1, 0.3 mm. The most common design thicknesses are 0.2mm, 0.25mm and 0.3mm.

(4) PIN pins are output on one side, and the spacing should be greater than 0.6mm.

(5) The length of the LCD crystal filling port is generally 10mm (MAX) long and 1.0mm (MAX) wide.

(6) The LCD should be added with alignment marks to facilitate alignment and bonding. The allowable tolerance of the alignment marks is 0.02mm.

3.2 Types of LCD Panel

(1) TN: twisted nematic:

(2) STN: Super twisted nematic;

(3) FSTN: Film Super twisted nematic;

(4) Normally white display mode;

(5) Normally black display mode.

3.3 Principles of LCD panel design

(1) The wires of different terminal electrodes on the same surface cannot cross. If the traces intersect unavoidably, use the transition point mark;

(2) Try to avoid crossing the upper and lower graphics. If it is unavoidable, it is better to arrange the crossing point outside the display area. If it must be arranged in the exhibition area, the area of the intersection should be controlled within 0.1mm x 0.1mm;

(3) The wiring should not be thin and long;

(4) The wiring should be far away from the cutting line, generally controlled at a position above 0.5mm from the cutting line. Because if it is too close to the cutting line, the edge of the screen will easily break the wire during cutting;

(5) Don't forget to set the cutting mark.

4. Exporting Gerber File 

When using AUTOCAD software to make a panel drawing, you need to set all the graphics content in the same layer, and then save the file as a DXF file under the R12 version. Import this file into the CAM350 file, set the condition to metric unit (mm), and do not make any changes to the other conditions. Finally, export the gerber file we need.

The above is the specific process that we use AUTOCAD to design LCD panels. If you have any other questions, please contact us!