The history of electroforming moulds, the principles and characteristics of electroforming

1、Preface

Entering the 21st century, the social structure with information technology and high consumerization has led to a flood of engineering plastic replicas. Electroforming technology has a wide range of applications as a reproduction technology in metal film manufacturing and mould manufacturing for casting. At the same time, as the manufacturing technology of engineering plastic moulds has taken on an important position.

2. Background of electroforming technology development

Electroforming was first started in Russia in 1841 by the conductive treatment of paraffin or plaster to make moulds for electroforming copper for crafts. But in the industry is widely used in 1950 ~ 1960 or so. The early period (19th century) of electroforming is mainly copper electroforming. It was limited to the reproduction of printing plates and the production of handicrafts such as statues and reliefs. The middle stage (early 20th century) iron electroforming gradually replaced copper to become mainstream, the application also expanded to rubber and plastic mould making. At a later stage (the second half of the 20th century) nickel replaced iron and became the mainstream of electroforming. Applications also expanded to the original discs, waveguide, casting and injection moulds, metal films, printed circuit boards, arts and crafts and many other aspects.

Copper, nickel, gold, platinum, silver and so on can do for electroforming processing materials, in the semiconductor, CD (MD) or DVD and other magnetic information recording, optoelectronics, microelectronics, DNA increase and other ultra-fine processing, have been applied. Electroforming has been used as an important processing means in the era of microelectronics technology.

3、The principle of electroforming

The principle of electroforming: like electroplating, it is an electrodeposition technology using electrochemical reaction. By dissolving the anode in the electrolyte containing the same ions as the metal to be obtained, metal is deposited on the master model as the cathode, thus forming a metal model that can replicate the prototype, and this is the principle of electroforming.

The main difference between electroforming and electroplating is that the product of electroplating is a composite of the part to be plated and the product. Electroforming, on the other hand, is simply the electrodeposition of the layer as the desired product. Eventually the plated layer has to be detached from the master model.

The quality of electroforming is related to the method of release and the metallographic characteristics of the electroformed metal. Application has the use of good ductility of nickel disc system of the mother type, with good conductivity of copper production printing line, with hardness and heat resistance of iron production stamping die, with good corrosion resistance and precious metal production of gold wire or decorative products, the use of silver sterilization effect of the production of DNA increase device and so on.

4、Characteristics of electroforming

The use of electroforming technology can produce other methods can not reach the reproduction of high-precision and detailed mould, can reproduce high value and high complexity of the shape. In addition, electroforming can also produce products that other methods cannot do, especially those that are very difficult to produce prototypes. During the electroforming process, the metal deposit is peeled off the prototype and can be disposable or reusable depending on the material of the prototype. The reusable prototype can be used several times, thus reducing the cost and increasing the efficiency of the electroforming process.

The cost of electroforming is reduced and efficiency increased. However, the technology of electroforming has room for further development. The standard of electroforming technology is closely related to the progress of material science, physical chemistry, as well as electrochemistry and the improvement of equipment.

The main technical and economic characteristics of the electroforming process are as follows:

①It has nothing to do with the shape and size of the product, as long as there is an electroforming tank it can be made;

② the physical and chemical properties of electrodeposits can be varied in a wide range;

③ the possibility of reproducing shapes with a precision of 50 to 100 nm;

④ hollow products and alloy products can be produced;

⑤ for mass reproduction products, there are advantages in terms of high precision and production costs compared to other methods;

⑥The efficiency of production is improved and it is beneficial to environmental protection.

5、The composition of electroforming system

The electroforming process and the production of prototypes are related to the method of obtaining the conductive layer (chemically physical), the stripping method using acids and bases, the nature of the electrodeposited metal, the equipment and the devices. The main systems include the metal to be electrodeposited, the electrolyte, the model, the equipment, etc. The fabrication of the prototype of the system is related to the material used for the prototype, and there are different electroforming solutions and processes for the electroforming of non-conductors and conductors.

6 Electroforming devices and equipment

The electroforming plant consists of non-metallic conductorisation equipment, master stripping equipment, power supply and electrolytic bath for electroforming. Depending on the purpose of electroforming, there are different types of equipment. For example, in order to metalise the non-metallic surface, the chemical plating equipment required is spray plating equipment and also immersion plating equipment; and the power supply is also used to switch power supply with good high voltage performance; and the anode is chosen as a spherical anode in consideration of the sufficient dissolution. The disc prototype electroforming uses a rotary disc electrode type electroforming device. This device allows the disc surface to be at an angle of 45°, so that the gas generated during the electroforming process can be easily precipitated. The plating solution is also used to circulate the plating solution by scouring the electroforming surface.

7 Recent technological trends

As electroforming requires a stable DC current, DC power supply equipment with very little AC factor has been adopted. At the same time in the plating solution analysis, hanging tool improvement, the introduction of calculation technology, etc. have new progress. Make electroforming metal performance has further improved. With the expansion of the application field of electroforming, traditionally rely on mechanical processing method processing gears, golf ball moulds, glasses, etc., have used electroforming method to manufacture moulds. And the precision of electroforming has also entered the era of nanometer level. For example, photolithography original plate or microelectronics products and TEM with micro, etc., are to use micro electroforming technology. This is because electroforming can reproduce the model very precisely from the prototype and can produce a mirror surface mould with a roughness of 40nm.

8 Conclusion

Although electroforming technology has entered the nano-age, it is little known. Its visibility is very low. What is used is still technology based on that developed 160 years ago. However, the process and the equipment have advanced considerably. In the future, it is necessary to further develop non-polluting or less polluting technology, and at the same time to carry out new development and development of electroforming technology according to the progress of physical chemistry, material science, electrical engineering, optics, mechanical engineering, economics, environmental science, etc., including the development of new alloy electroforming technology suitable for electroforming