Technology analysis of mobile phone mold making

1.Selection of mobile phone shell material

The mould of mobile phone is expensive, and the material price of the product is not very expensive; the role of the shell in the mobile phone: it is the support frame of the whole mobile phone; positioning and fixing the electronic components; carrying all other non shell parts and limiting. The shell is usually molded by engineering plastics.

1. Common materials for shell

Abs: high fluidity, cheap, suitable for parts with low strength requirements (components not directly impacted and not subject to structural durability test in reliability test), such as the keypad frame (LCD frame) inside the mobile phone, etc. There are also commonly used in parts to be electroplated (such as buttons, side keys, navigation keys, electroplated trim, etc.). At present, Qimei pa-727, pa757 and so on are commonly used.

PC + ABS: good liquidity, good strength, moderate price. It is suitable for most mobile phone cases, as long as the structure design is more optimized, the strength is guaranteed. Ge color c1200hf is more commonly used.

PC: high strength, expensive, and poor liquidity. It is applicable to the case with high strength requirements (for example, two shells in the flip phone that match the rotating shaft, two shells of slide rails and slideways in the slide cover machine without standard slide rail module, etc., so PC materials must be used at present). Ge Lexan exl1414 and Samsung hf1023im are more commonly used.

2. The following two points should be paid attention to in the application of materials:

Avoid reducing the risk of strength, and PC materials are used for any part, which leads to forming difficulties and cost increase;

In case of incomplete grasp of strength, the mold supplier should be clearly informed when the tool review is being reviewed. It may be possible to produce T1 products with PC + ABS first, but it is not excluded that PC materials will be used later when the strength is not enough. In this way, the die supplier should consider the shrinkage and the drawing angle of special parts in the design of the mold.

Generally, the shell is composed of upper and lower shells. The upper and lower shell shapes can be coincident theoretically. However, due to the influence of manufacturing precision and injection parameters of the mold, the size of the upper and lower outer dimensions is inconsistent, that is, surface scraping (surface shell is larger than the bottom shell) or bottom scraping (bottom shell is larger than surface shell). The acceptable surface scraping is less than 0.15mm and the bottom scraping is acceptable less than 0.1mm. When the zero section difference cannot be guaranteed, the surface shell of the product shall be larger than the bottom shell as far as possible. Generally speaking, the surface shell has more key holes, and the forming shrinkage is larger, so the shrinkage is larger, generally 0.5%. The shrinkage of the bottom shell is smaller, so the shrinkage is smaller, generally 0.4%, that is, the shrinkage of the surface shell is generally 0.1% larger than that of the bottom shell. Even if the two shells are of the same material, it is also necessary to remind the mold factory to take a smaller shrinkage rate when making the die.

3. In the manufacturing of digital camera mould, many mold products are also developed based on ABS + PC.

The general process of making silicone mold for mobile phone is as follows;

Preparation → rubber pressing → painting → stamping → radium carving → finished product packaging.

1. preparation: in fact, the raw rubber block to be manufactured and some ingredients (mainly color powder and other additives) are fully mixed, then extruded into plate shape, and then cut into the required strip rubber for later pressing

2. rubber pressing: it is easy to accident for the main process. If the rubber parts are very thin or narrow, it is possible to tear them when they are removed (the reason may be that the wall of rubber parts is too thin and too narrow, and the mold temperature is high at that time, about 100 ℃, and the rubber parts are too soft and the strength is not enough). See one side of the outer sealing part of buzzer in 2024 as an example; At the same time, there will be a rough edge (which can not be punched in the subsequent process) like the forming of this kind of edge can not be removed.

3. Painting: pay special attention to painting. The rate of scrapping is very high. Generally, two coats of paint should be sprayed, which are of different colors for the later radium carving. After spraying, the next procedure will be followed

4. Stamping: it is to cut off the non flying edge and leave the key needed. In this process, rubber can not be allowed to produce rough edges; often, too small fillets will produce flying edges, one not less than 0.5mm.

5. Radium carving: laser carving is to lay the key flat, generally have the manufacturing tools and positioning, and then the laser carves out a layer of paint on the key, and calls out the words on the key, such as the number key, which is transparent; if it is two layers of paint, only one layer is carved out, leaving a layer, such as OK answer key, and the key is, one layer of paint is red, and the other is blue.

The method of making key characters of silica gel

The characters on the surface of the silica key generally have the following manufacturing methods:

1. screen printing: the screen and the bottom are divided. When printing, the surface of the key is generally sprayed, then the font and symbol of the screen printing are printed on it, and then the protective oil is sprayed. The bottom is generally transparent key, there are screen printing hollow word cover background color and screen printing solid font cover background color. For the key indicating that the arc surface is large, the method of transfer printing can be used, the font can be corroded on the steel plate, and the ink is transferred to the surface of the key with the glue head. The transfer printing is used in the toy industry.

2. if the characters require light transmission effect, most of them are spray and laser carving. After injection of transparent keys, spray ink on the surface of the key, then laser out the characters that can be transmitted through light, and then spray a layer of protective oil. For the red symbol, you can first shift red on the top of the key, and you need to print the whole surface. After spraying, you can print the ink on the surface to see red. Other colors are similar.

3. the buttons requiring electroplating effect can be used for water plating and vacuum plating. At present, the common electroforming mold with Yin and Yang effect on many direction buttons is required. The boundary of the process is clear and the appearance is beautiful. It is the effect that can not be achieved directly by shading on the mold. Two color injection molding is generally used on a key that needs light transmission and electroplating. PC can not be electroplated, ABS can be electroplated. The requirement of two-color injection molding is to inject PC and ABS together. The place where ABS is electroplated is plating effect, and PC part can be transparent. Vacuum plating can also make light transmission symbols at present, but the effect of vacuum plating makes people feel more floating, no electroplating effect is good.

The surface of mobile phone button is usually a processing method for text processing on the surface of key painting. It is generally 0.04-0.06 in diameter. Then we fill the text with lines with spacing of 0.04-0.06. In this way, we have developed a path for the laser. The laser can cut off the paint along the path.

If we want to do laser carving well, it is important to speed up, the method of filling light is not enough. Another way is to give the path of laser as CNC does. The boundary will be clear, because the laser will generate a large energy when triggering, which will cause the problem of breakthrough and the appearance of serration.


About JasonMould Industrial Company Limited

Jasonmould is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: JasonMould Industrial Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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