CD Print Quality Control and Analysis of Common Problems

In the past, color graphics on optical disks were mostly accomplished using a screen printing process. However, in recent years, with the continuous development of optical disc technology, the application of DVD optical disc products has become more and more extensive, and the requirements for the decorative quality of optical disc surfaces have become higher and higher. In order to cater to this market development trend, while ensuring the playback function of CD products and higher sound and picture quality requirements, waterless offset printing (in most cases, screen printing and waterless offset printing) has become a new optical disc printing technology. .

This is the first time we have discussed in depth the optical and disk printing technologies. We know very little about this particular technology. Through interviews with technicians from several well-known domestic CD-ROM manufacturers, their rich experience has benefited us a lot.

Quality control points

Due to the different substrates, there are many essential differences between optical disc printing and traditional paper media printing. However, in fact, CD printing is not as complicated as traditional paper media printing. As long as you master the quality control points, you can print products that satisfy your customers. In this interview, most technicians believe that controlling the following factors is critical to improving the quality of CD-ROM printing, and describes their own experience in these areas.

1. Selection and Testing of Optical Disc Printing Consumables

(1) Special UV ink

The special UV inks are used in the printing of optical discs. At present, there are many product brands sold on the domestic market, such as French Dolby, American Sha colorful, Japanese DIC ink, and FUJIN (Kunshan) FUJ ink and Rio Tinto. Oak people ink and so on.

1UV screen printing ink

UV screen printing ink for CD printing requires high saturation, good transparency, good thixotropy, and fine and uniform ink particles. In order to ensure the ink pigment particles pass through the mesh, the particle size should be 1/1 of the mesh. 4-1/3. UV inks for CD, VCD disc printing, in addition to the above requirements, should also have good adhesion with PC (polycarbonate) materials. UV inks used for printing on DVD-based discs have a small degree of shrinkage during UV curing; and the ink layers are thin and uniform to minimize the flatness and high-definition portrayal of DVDs during UV ink curing.

2UV waterless offset printing ink

UV water-free offset printing inks for optical disc printing require high transparency, fine pigment particles, strong coloring power, low viscosity of the ink, low thixotropy, no high yield value, and good rheological properties.

In addition to the requirements for the basic performance of special UV inks, there are many artificial regulations in the printing of optical discs. According to Mr. Fan Weichang, General Manager of Guangdong Weiya Optoelectronics Co., Ltd., when processing external single discs (such as printers, digital cameras, scanners, etc.), the inks used by disc printing companies must comply with international environmental protection requirements, that is, corresponding The green environmental protection certificate, the products printed with this type of ink can enter the international market.

(2) UV curing device

The core component of the UV curing device is a UV lamp and a reflector. The function of the device is to cure the ink on the surface of the optical disc by the irradiation of the UV lamp. This device is very critical in optical disc printing equipment. Each group of CD-ROM screen printers is equipped with a UV curing device, while the CD-ROM offset printer only has a set of UV curing devices after 4-color printing.

Mr. Zhou Wei, Head of Printing at Shanghai United Optical Disc Co., Ltd., reminded everyone that the spectral characteristics of the UV lamp must match the spectral characteristics of the ink. Otherwise, the degree of drying of the UV ink on the surface of the optical disc will be affected, resulting in ink drop and other quality problems.

(3) scraper. Blanket and tray gasket

The quality of scraper and tray gaskets plays an important role in whether the screen printing is solid and the dot is clear.

The quality of rubber blankets and tray gaskets is closely related to the quality of waterless offset printing. Because, in the waterless offset printing, the graphic is transferred from the printing plate to the blanket, and finally transferred to the printing surface of the optical disc.

(4) Testing equipment

Detection is an indispensable part of high-quality optical disc printing. The general inspection contents are: under the standard light source, the color difference of the printing surface of the optical disc is detected, and the UV energy detector is used to check whether the spectral characteristics of the UV lamp and the UV ink match. . At present, the detection devices commonly used in optical disc printing include standard light sources and electronic calculation equations. UV energy detector, ID code checker, etc. Others are professional testing equipment equipped on printing equipment for online real-time monitoring, such as Papageno, BaslQr disc detection system, in which Papageno disc inspection system is used to check whether the disc print surface defects, Bas, er disc detection system for Check for discrepancies on the disc information surface and correctness of the dial number.

2. Film production quality

At present, China's CD-ROM printing has not yet introduced CTP (computer-to-plate) technology. Therefore, the pre-press link still uses the traditional pattern-making method. If the customer provides an electronic file, the film needs to be output by a laser photosetter. Therefore, the quality of the film will directly affect the final print quality of the optical disc. Depending on the type of printing used, prepress staff should make appropriate adjustments and handling.

According to Mr. Wang Guokang, director of printing technology of Shanghai Xinsuo Music Co., Ltd., the requirements for the quality of film production are: the number of screens for screen printing films is controlled at 1 33 lines/inch or less, and the dot reproduction range is 10 %-a 90%, line width of text and thin lines is not less than 50mm; water-free offset printing film is controlled within 200 lines/inch, and dot reproduction range is 2%-98%.

In order to ensure the production quality, Guangdong Weiya put forward some specific requirements for the film provided by customers (for example, screen printing).

1 film requirements are Zhengyang tablets, film on the top.

2 In the main pattern of people or scenery and some non-ground patterns with dark and light colors, the number of screens should be controlled at 80-1 20 lines/inch.

3 The printed graphic must be within the outer diameter of 11 7mm and the inner ring diameter is 20mm.

4 There must be an alignment crosshair on each film. It must be marked outward at a distance of 3 mm from the outer diameter of the disc (ie, a diameter of 1 26 mm) with a tolerance of 0.1 mm. The alignment line is at the top, bottom, left, and right positions of the center of the pattern. The alignment line length is 1 5mm, width 0.1mm, as shown in Figure 1.

5 Number of the plate number and printing color (PANTONE color code) or C, M, and 丫. The K color scale is attached to the film surface.

(to be continued)