As the world becomes more connected, the demand for electronic devices and systems increase. The aerospace, automotive, medical, RF microwave, industrial, and electronics industries require components that are lightweight, machined with precision, and that will serve as a barrier from EMI and RFI emissions. OEMs and their Design Engineers have to decide which manufacturing process will be the most functional and cost-effective for their products.
The chemical etching process, also known as photo etching, photochemical machining, and photochemical etching is ideal for EMI/RFI board level shielding as well as printed circuit board microelectronic components found in RF microwave, optoelectronics, space level modules, interconnect, medical device and automotive wireless connected systems. Below are five reasons why OEM’s can’t afford to overlook this metal fabrication process.
1. Variety of Metal Etching Capabilities
The most common metals used in the production of electronic components are compatible with the metal etching process and not limited by the material’s properties.
–Copper etching: Except for silver, copper has the best electrical conductivity, and it is highly effective in weakening magnetic and electrical waves. It also has excellent thermal conductivity, solderability, strength and corrosion resistance. Since copper tends to oxidize, post plating will enhance corrosion resistance. Copper components, such as lead frames, EMI/ RFI shielding, contacts, pins, terminals, connectors, and bus bars are widely used in the printed circuit boards found in many electrical systems. Not to mention that copper is a more sustainable choice for manufacturers because it is 100% recyclable.
–Beryllium Copper: BeCu is highly conductive and the strongest of the copper alloys (also known as spring copper) which makes it easy to form and retain complex shapes such as contacts and springs.
– Brass etching: Brass is a copper and zinc alloy also known for its high electrical, thermal conductivity, strength, and corrosion resistance. It is a highly workable metal which makes it suitable for forming and retaining shape, thus perfect for springs, contacts, connectors, and lead frames, EMI/RFI shielding and bus bars.
–Phosphorous Bronze: A bronze alloy containing copper and zinc is an excellent choice for electronic components due to its superior spring qualities, high fatigue resistance, excellent formability, and high corrosion resistance. These properties make it an attractive option for battery contacts and springs.
– Nickel/Silver: An alloy made of copper, nickel, and zinc is used mainly in electrical components such as EMI and RFI shielding because of its high corrosion resistance, and solderability. Therefore, it does not require plating. The material is also hard, malleable, ductile and nonmagnetic.
– Steel: Steel is not as electrically conductive as the other metals, although the addition of tin plating makes it highly conductive and solderable in EMI/ FRI shielding components. Cold Rolled Steel, because of its strength, has high formability, spring properties, and shape retention.
– Stainless Steel etching: This type of steel is highly resistant to moisture-related corrosion and has excellent thermal conductivity, making it a preferred choice in flat springs, filters, and EMI/RFI shielding and enclosures.
Photo etching is not limited to a metal’s strength whether it is hard, soft or brittle. On the other hand, stamping has issues with some hard, soft or brittle metals, and hardness is a consideration in the wire EDM and water-jet cutting processes.
2. Resistant To Thermal Stress
The high temperatures (often present in the different metal fabrication processes) can cause thermal stress such as metal weakness or deformities. These unfortunate effects can alter the metal component’s performance by reducing conductivity and increasing surface friction between two or more circuit board elements.
How does chemical etching measure up compared to other manufacturing processes?
While heat is present in several manufacturing processes for electronic components, chemical etching is the only method where parts do not incur thermal stress and deformations.
Even though the temperature may increase in the etching of some metals, the properties remain unaffected. The chemical etchant washes away the metal sheet parts simultaneously, in contrast to a localized point of contact from either an electrical charge or gas. For this reason, laser cutting and wire EDM can leave thermal stress along the edges. While the stress may not be significant, it can still interfere with functionality.
3. Metals Remain Burr-Free
Another adverse effect of the metal fabricating processes is the presence of burrs. Laser cutting and wire EDM can leave micro burrs on the metal’s surface, while stamping can leave partial burring. Any burring at all can alter the component’s performance and increase the risk of malfunction in electronic systems.
Here are just some of the issues that can occur:
1. Electrical short circuits from loose burrs
2. Interference interruptions
3. Plating build up at the component’s edges
4. A decrease in the part’s formability
5. Inaccurate dimensional tolerances
6. Scratches on the surface can affect mating components
These issues are the reason that OEMs should consider metal etching as a favorable alternative. The chemical etchant dissolves and washes away any unwanted material. The results are smooth surfaces and precision-etched edges, eliminating the need for costly secondary deburring operations.
4. Capable Of Etching Thin Materials With Complex Designs
Over the past decade, electronic devices have become smaller, therefore creating a demand for smaller scale, lightweight components with intricate designs. Typically, these types of microelectronic pieces are machined on thinner metals to decrease weight and require tighter dimensional tolerances.
Chemical etching is the best machining method for complex patterns such as lead frames, filters, and EMI shielding components because features such as angles, holes, and slots are machined simultaneously. This process saves time and money compared to laser cutting, wire EDM and stamping.
Another photo etching feature is the ability to half-etch on the metal surface. These score lines which are usually etched to 50% of the metal are useful in EMI/RFRI Shielding and other electronic components that need to be formed into a 3-dimensional shape. The half-etch lines make it easy to bend without deformation.
5. Easy To Modify Prototyping
The ability to test designs and make modifications is an essential step in the prototyping stage. The chemical etching process makes part revisions a snap with low-cost digital tooling. Hard conventional tooling can cost thousands, whereas, digital photo tooling is only a fraction of the cost. Also, if more than one electronic part design requires the same material and thickness, they can be arranged on the same tooling, known as, compound tooling. This available option can lower the cost and speed up the prototyping process.
The above five chemical etching advantages are essential to consider when choosing a manufacturing method that will keep electrical systems functioning at optimal efficiencies and without interference.
Advanced Metal Etching has been providing the electronics industry with electronic components for over 25 years. We have multiple etch lines to accommodate all types of metal and projects for prototyping or large production runs. Our in-house tin plating line and other secondary operations will enable OEMs to get their products out to market faster.