what is Electroforming
Learn everything about the technique, types and benefits of Electroforming
introduction
Electroforming is a metal forming process by means of electrodeposition, similar to Electroplating and Electrorefining. The electrodeposition process takes place in an electrolytic bath and involves two electrodes (an anode and a cathode) and an electrolytic solution. The mandrel is placed in the bath and the electrodes pass a DC through the solution. The DC converts metallic ions into atoms that are continuously deposited on the conductive areas of the mandrel until the desired metal thickness has been achieved.
Compared to other traditional metal forming technologies, for example casting, forging, stamping, or deep drawing, Electroforming can deliver mass volume at superior accuracy and extreme design complexity, due to the fact that it can replicate the shape of the mandrel at extreme accuracy.
Electroforming is also an additive manufacturing process specialized for the production of high precision metal parts. Its uniqueness is that you can grow metal parts atom by atom, providing extreme accuracy and high aspect ratios. Typical precision of a electroformed part goes down to 1 to 2 μm, which is beyond what most other manufacturing technologies can reach.
Veco, as the world leader and largest independent supplier of Electroforming, has been moving the industry forward, with unparalleled experience of Electroforming, advanced lithography technology, and accumulated knowledge of metallurgy. Veco’s unique Advanced Lithographic Electroforming, also referred to as Advanced Photo Electroforming, is predominantly done with nickel, followed by palladium nickel or copper, depending on specific demand (learn more about materials).
from traditional Electroforming to Advanced Lithographic Electroforming
Photolithography refers to the process where a geometric design pattern is projected to a photosensitive resist on a substrate by the means of light. Traditionally, this is done by placing a mask on the photoresist layer and exposing light to the entire mask. Laser Direct Imaging is the next step in the evolution of the Photolithography technology.
As the world leader in Electroforming technology, Veco is the first in the industry to apply the advanced Laser Direct Imaging technology in high precision metal parts manufacturing. At Veco nowadays, 90% to 95% of our photolithography process is done by Laser Direct Imaging. The combination of LDI and our leading Electroforming technology has enabled us to further push the boundaries of the industry with our Advanced Lithographic Electroforming, providing our customer with high precision metal components in higher quality, at lower cost, and with quicker turnaround.
higher quality
lower costs
quicker turnaround
Higher resolution (between 25.400 and 63.500 dpi) is possible with LDI, which is beyond traditional film quality and can potentially replace glass masks.
Moreover, In case of multi-layer electroforming, the second/additional layer needs to be perfectly aligned. Doing this manually is inaccurate and time consuming. With the Laser Direct Imager, perfect alignment can be done automatically and efficiently.
Laser Direct Imaging (LDI) is a maskless photolithography technology. Compared to the conventional way that needs a mask for exposure, using the maskless photolithography process means reduction of the costs of glass masks. One such mask costs around 5000 dollar.
In product development and prototyping , it is common to have corrections or different versions of product designs, which means more masks will be required, and more costs involved.
The elimination of traditional masks in the procedure not only reduces tooling costs, but also reduces lead time.
Production of one mask needed takes up to a week, and when there’s corrections the procedure needs to be repeated again. With maskless LDI, on the contrary, corrections can be processed immediately in the next exposure. The LDI is capable of projecting high resolution images directly from a CAD file, thus allows fast and easy adjustments to be done to new photoresists.
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Electroforming process overview
Veco’s Advanced Electroforming process is a unique combination of unparalleled industry experience of Electroforming, advanced lithography technology, and accumulated knowledge of metallurgy. It comprises 6 steps.
1) Cleaning
A metal sheet substrate is cleaned and degreased.
2) Coating
The cleaned metal ‘blank’ is then coated with a light-sensitive photoresist.
3) Exposing
The metal sheet is then exposed to ultra-violet light, which hardens the photoresist.
4) Developing
After the image is transferred by UV exposure the substrate is developed, rinsed and dried.
5) Deposition
An electrolytic bath is used to deposit metal onto the patterned surface.
6) Harvesting
The electroformed part can be harvested from the mandrel, once the material is plated in the desired thickness.
7) Inspection
Full inspection by experts.
Electroforming key features
unique hole configuration
besides straight holes, it is also possible to achieve special bell mouth hole shape
thickness range
thickness range 5 – 1200 micron
feature size
feature size down to 2 micron
tight tolerance
tight tolerance down to +- 1 micron
design flexibility
complex shapes and design configurations with different materials
3D structures
complex 3D structures can be achieved by growing additional layers in different directions
high quality
burr-free, stress-free components with ultra smooth surface and clear edges
cost efficiency
highly cost efficient from prototyping to industrial scale mass production
types of Electroforming
Overgrowth Method
Thick resist method
Surface replication
Overgrowth Method
Plating Defined Electroforming: the Overgrowth Method
Plating defined electroforming is also referred to as an overgrowth method.
Fig. cross section of an overgrowth product.
It uses a thin photoresist pattern to shield parts of the conductive substrate. A light-sensitive coating is applied to the conductive surface, and it will polymerize where it is exposed to UV light. Metal grows over the photoresist and the thickness of the product exceeds the thickness of the photoresist, hence the process is also known as overgrowth. Note that outer corners will round off during growth, while inner corners will be sharp.
The process is mainly used to make sheets with small conical orifice s for filtration and (ink)jetting.
Thick resist method
Photo Defined Electroforming: the Thick Resist Method
Photo defined electroforming is also called the thick resist method.
Fig. cross section of a hole made by thick resist
In some cases, it is desired to make the product thicker. This is when the thick resist method is applied. A thick pattern of photoresist is used during photo defined growth, such that the thickness of the product does not exceed the thickness of the photoresist.
Aspect ratios up to 1 can generally be achieved with ease. The exact limits depend on the size and geometry of the products .
Surface replication
Surface Replication with Electroforming
The electroforming process allows for extremely precise duplication of the mandrel.
Fig. Example of surface replication by Electroforming
The high resolution of the conductive patterned substrate allows finer geometries, tighter tolerances, and superior edge definition. This results in perfect process control, high-quality production and very high repeatability.
Electroforming is therefore perfectly suitable for high precision surface replication at low cost and in high volumes.
benefits of Electroforming
1) Cost reduction
With Electroforming, there isn’t substantial investment on equipment to start a production. This makes Electroforming cost effective from prototyping to mass production. With many manufacturing techniques, you’ll need additional tooling or machinery before you can start the process. Take die-cutting for example a punch will be required to invest before production can be arranged.
With many other metal fabrication methods such las laser cutting or milling, every piece is handled one by one, resulting in longer lead time especially with larger volumes. Electroforming on the other hand allows you to simultaneously grow a large number of high-tolerance parts in one go, which makes it very suitable and efficient for large volume production. Production cost can therefore be reduced from volume production and efficiency improvement with Electroforming.
2) Perfect replicability from prototypes to mass production
The electroforming technology is known for perfect replicability and reproducibility, due to the fact that the process allows for extremely precise duplication of the mandrel. The high resolution of the conductive patterned substrate enables finer geometries, tighter tolerances, and superior edge definition. This results in perfect process control, high-quality production, and very high repeatability.
With metal fabrication methods like Milling, the machine needs to mill every piece one by one, which directly affects the time that is required to produce larger volumes. This is also the case with many other processes like laser procedures: every metal part needs to be individually cut out. Electroforming on the other hand allows you to simultaneously grow a large number of high-tolerance parts in one go. The more metal pieces that are needed, the more interesting electroforming becomes.
Electroforming is therefore perfectly suitable for high precision surface replication at low cost and in high volumes.
3) High-precision metal parts
With the trend of miniaturization, manufacturing industries see an increasing demand for metal parts of very high precision. In the new generation of production development and design, components at micron or even submicron level are in the demand— demand that conventional techniques such as laser cutting or stamping can’t meet.
Electroforming in combination with advanced lithography process can be the technique to meet the demands of miniaturization by providing the next level high-precision sheet metal parts. With Electroforming, high precision sheet metal components can be made with extreme accuracy. The standard deviation of most critical feature can be only ~0.1 µm on one single part.
4) Freedom of design
The process of manufacturing high precision components straight from CAD design files is an obvious indicator of freedom of design. Without large investment to start production, Electroforming can be used for fast prototyping or mass production, or more ideally both.
Electroforming is thus very suitable for the future-proof experimental approach for next generation of product design and development: a design method where various versions of component designs are made to see which one works best. Instead of using different manufacturing method and handling with multiple suppliers for different components, Electroforming can be the one stop solution for different designs from prototyping to industrial production.
5) Short lead and delivery times
With Electroforming, short lead time and delivery time can be realized. Compared with other manufacturing technologies which requires more time consuming processes, Electroforming process is much more time efficient. In stamping, for example, a die may take up to months to build. In CNC Punching, a die is available within days to weeks. After that the realization of the die, the creation process is yet to be initiated. A mold that is used for Electroforming, on the contrary, can be produced within hours with the Laser Direct Imager.
Electroformed components can therefore be created and delivered within 3 weeks — and usually even sooner, depending on the complexity of the project and co-development procedures.
6) Multi-layer structures
Electroforming is not limited to producing 2D structures because additional layers can be grown by repeating the deposition process. These additional layers can reinforce thinner electroformed parts, making them easier to handle and less fragile. Moreover, these additional layers can be grown in different directions, which can provide more delicate structures to meet complex design and functional demand. The multiple layer capability brings new possibilities for many industries that demand complex precision metal solutions.
7) Straight side walls, free from burr or stress
With Electroforming perfectly straight side walls can be achieved with no burr or stress, which is important for many components. This demand is hard to be met with other techniques. With traditional laser processing methods, for example, you will often end up with side walls that are relatively rough on the edges due to heat influence.
8) Special conical hole shape with non-clogging benefits
Electroforming allows you to manufacture components with very unique conical hole shape. This enables us to provide high performance filtration sieves with self-releasing advantage, the filter won’t easily clog and stays clean for a longer use.
Besides filtration the unique conical hole shape sees applications in various industries including medical. Our Electroformed nebulizer nozzle plate plays an essential role in the state of art nebulizer, releasing millions of micron-sized droplets per second through its unique geometry, forming a perfect fine mist for targeted delivery to the lung.
9) Alteration of material properties
Electroforming allows for alteration of material properties, so different material properties can be achieved with the same material. When altering material properties doesn’t suffice, for example if high corrosive resistance is demanded for special application, or a particular material is necessary to be in contact of human skin, that’s when coatings comes in. A layer of material such as palladium or gold can be coated followed by Electroforming process.
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