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Hello! I'm TR of R&D department.
In this article, we would like to talk about the development of our low-stress nickel plating technology for the nickel electroforming process, which is applied in various fields of electronic device products.
The potential of electronic devices expanded by nickel plating
Nickel electroforming aimed at producing molds with fine uneven shapes is a technology applied in various product fields such as CD and DVD stampers, inkjet printer heads, organic EL fine metal masks, MEMS, and nanoimprints.
Generally, the electroforming is a technology to utilize a nickel plating film peeled off and then transferred the patterning on surface of the substrate after forming by electroplating on a substrate such as silicon or resin that a conductive layer is formed on the substrate.
In order to peel off the plating film and use it, it is necessary to have a certain thickness so that the structure formed on the surface can be maintained and handled appropriately according to each application.
Three points when considering nickel electroforming
There are 3 points for considering nickel electroforming.
1．Fine pattern formation
The photolithography process is generally used to form fine patterns by plating. It is also possible to create wiring patterns with line widths / pitches on the order of several μm. In electroforming, a mold release agent is applied to the surface to make it easier to remove from the mother mold.
2．Internal stress of plating film
One point to keep in mind when plating is to properly control the internal stress of the plating film. Generally, a stress relaxation agent is added to the plating solution used to suppress warpage. Without proper stress relaxation, the peeled plating film will warp and difficult to handle.
3．Film thickness uniformity
The faster the plating speed (higher current density) and the thicker the plating film thickness, the larger the film thickness difference between the center and edge of the substrate tends to be. In order to improve the uniformity of the film thickness while keeping the plating speed as high as possible, it is important to optimize the conditions such as the structure and dimensional accuracy of the plating tank, the position accuracy between the electrodes, that is, the anode (pure nickel plate in the case of nickel electroplating) and the cathode (product substrate) and the stirring of the plating solution.
Tosetz achieves low warpage thick plating and high film thickness uniformity!
We specialize in fine wiring plating on silicon wafers and substrates.
We have abundant knowledge of nickel plating, NiFe, and NiFeCo magnetic film plating, and have the know-how to realize low warpage thick film plating and high film thickness uniformity and respond to various evaluation requests from customers.
The specific data of our company is described below.
1．Control of internal stress of plating film
By controlling the plating conditions and additive conditions, it is possible to produce a low-stress nickel plating film with a thickness of several hundred μm. The graph below shows the changes in the plating film thickness and internal stress, the stress is small at the range from 100 to 150 μm. It shows to be able to control the plating conditions for the purpose of minimizing the warpage of the substrate.
Changes in internal stress with respect to nickel plating film thickness
2．High film thickness uniformity
With the equipment technology cultivated over many years, it is possible to keep the film thickness variation in the 8-inch wafer size within ± 5% of the target film thickness. For electroforming products that require precision, a flattening process may be required after the plating process because high dimensional accuracy in height (film thickness) is required. The larger the height variation, the longer the flattening process will take, which will increase the cost. Suppressing height variation greatly contributes to the reduction of manufacturing costs.
Application fields of low-stress nickel-plated electroforming
The application fields of low stress nickel electroforming are introduced below.
1．Inkjet printer head
Nickel electroforming technology is used for the nozzles of printer heads that spray ink from inkjet printers.
2．Fine Metal Mask (FMM)
In the organic electroluminescent display（OLED）manufacturing process, metal masks are used to deposit light emitting materials on glass or film. Since it can be made finer than the conventional etching method, High-resolution OLED can be achieved by using a mask manufactured by the plating method.
3．Nanoimprint
In nanoimprint technology, which was developed for the purpose of forming fine patterns, nano-order trenches and via structures for processing fine wiring can be formed on a substrate by applying a resin material on a substrate and then curing the resin while pressing a mold. Molds made by nickel electroforming can be applied in the case of thermal cure method.
Lastly
What do you think?
At Tosetz, we will support the development of our customers' products by realizing low warp thick film plating of nickel plating, NiFe, and NiFeCo magnetic film plating and high film thickness uniformity!
Click here if you are interested in Tosetz.
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