Our customers have very high standards when it comes to selecting the source of their electroformed parts. They look for extreme capabilities in areas like:
• Feature size
• Feature controllability
• Surface uniformity
• Batch consistency
• Component ruggedness
In other words, our customers want parts whose features and surfaces are uniformly the size and shape specified (e.g., not warped or rough). They also want parts durable enough to perform well in the application environment for which the parts are intended. Success factors generally involve the condition of the electrolytic bath during plating.
• The chemical makeup of the electrolyte bath
• The chemical balance and pH of the bath
• Cleanliness of the bath
• Bath temperature
• Room temperature
• Current density
Electroplating is a process that uses electrical current to bond metal to metal in an electrolytic cell, or container, filled with a chemical mixture called a bath. Besides the bath the cell also contains a positively charged source of metal (the anode) and a negatively charged target (the cathode). In electroforming, the cathode is the mandrel’s metal layer and any metal deposited there.
The electrolytic bath consists of dissolved salts (copper sulfate, for example) that provide ions to enable the flow of electric current through the bath from anode to cathode. The electric current ionizes the anode’s metal; the ions are dissolved in the bath and then flow to the cathode where they bond to, and build up, the electroformed part. The rate at which metal is added (plated) to the cathode is proportionate to the current density — i.e., the more electric current applied, the faster the plating.
Current density is a key parameter that impacts quality of the part. If plating happens too fast or too slow the part’s surface is more likely to be uneven. Another consequence of too-high current is stress — i.e., pressure within the deposit that can cause metal to warp, shrink, crack, or even break, once deployed in the customer’s application.
Another reason chemical balance is key is so that salts do not precipitate out of the bath, as these solids could strike the part and cause damage. Environmental dust could also cause damage if it were allowed to get into the bath. Even a 2-micron size piece of lint can do serious damage to a circuit with features in the 5-micron range. To protect against such hazards, Metrigraphics has developed and strictly follows a number of best-manufacturing practices, process controls, and quality assurance procedures.
Here are five of the most significant ways Metrigraphics ensures the quality of its electroforming process:
Knowledge capture and reuse. When a customer comes to Metrigraphics with a new project, our deep knowledge captured from thousands of previous projects over many years enables us to gain quick and clear insights into process design and set-up for best results at lowest risk with fastest turnaround.
Constant monitoring. We continually monitor key parameters like current density, chemical balance, and bath and ambient temperature to ensure that the process stays on track with the recipe prescribed for a particular part. This helps achieve uniform results consistent with a given recipe, but also provides a benchmark against which to potentially fine-tune the recipe for even better results.
Visual parts inspection. Electroplating is a “fluid” process — conditions of the bath will drift with time and with the number of batches processed. That’s why we visually inspect parts as they come out of the bath to make sure that specifications such as geometry, surface smoothness, and feature size are being met. If they’re not being met then we will take mitigating measures such as replacing bath filters, replacing the bath, or adjusting the recipe.
Quality of manufacturing facilities. Whether your electroformed part can meet design specifications, perform as intended in your application, or stand up to environmental challenges has a lot to do with the capabilities of the manufacturing equipment and processes involved in making the part. Those capabilities include state-of-the-art systems for computer-aided design, photolithography masking and imaging, the layering of metals at an almost atomic level, and ultrapure manufacturing equipment and clean rooms.
Electroforming manufacturing experience. Advanced skills are required throughout the electroforming production cycle. Product and process engineers must know what will work and what won’t so as to meet the application’s design, mechanical, environmental, and cost criteria in high volumes at high yield — and within tight market windows.